Should You Play GTO Against Bad Poker Players?

Should We Play GTO Against Bad Poker Players?
This article was written by contributor Lars Kyhnau Hansen

One of the most talked about concepts in poker in recent years is GTO, which stands for Game Theory Optimal. In short it’s an attempt to play in a way, so that our opponents can’t beat us, no matter what they do.

In the classic game of rock, paper, scissors, the GTO style would be to randomly select either rock, paper or scissors a third of the time.

In poker, GTO means to always have a perfect mix of value hands and bluffs, when we bet or raise. And to neither call nor fold too much, when our opponent bets or raises.

The question is, do we want to play that way against bad players though, which we find in large numbers in online micro stakes games and low stake live games?

I think generally the answer is no, but let's dig a bit deeper!

Should You Use GTO Versus Poker Fish or Not?

For instance there is no need to feel we have to sometimes raise a fish on the river as a bluff. This is because we know he is probably unable to fold a hand like top pair.

There is also no need to feel we have to defend against 3-bets a certain amount of the time, if we know for example from our PokerTracker HUD, that a tight nitty player has only been 3-betting 2% of the time over a sample of say 2,000 hands.

We know he almost certainly has AA, KK, QQ or maybe AK, when he 3-bets, and hardly ever a hand like A5, 87 or 66.

So we can safely fold our AQ (for example) and avoid a lot of expensive situations postflop.

There is however one situation, where I think, game theory is useful against bad players, and that is, when we are facing aggression from them.

Especially when it happens in an unorthodox way like a donk bet or a weird bet size.

The reason for this is the same reason why game theory is useful when facing aggression from very good players.

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Using Game Theory Versus Solid Professional Poker Players

Very good players and very bad players have one thing in common, and that is, that it is difficult to put them on a hand.

If a world class player like Phil Ivey bet 2 times the pot on the river, we are in a tough spot, because he is perfectly capable of doing this as a bluff and also for value.

And this is why to not be exploited by Phil Ivey, we need to call the right amount of the time. Nothing more and nothing less.

By the way, he discusses this in more detail himself in his new advanced poker training program.

If he bet 2 times the pot, his bluffs need to work 67% of the time, and therefore we should call exactly 33% of the time.

This is also sometimes called MDF or Minimum Defense Frequency. If we call any less, Phil Ivey can push us around, and if we call more, he can value own us.

As a general rule fish are not going to own us or push us around, because they are typically not able to figure out what we might be doing wrong.

But at the same time they are also difficult to hand read, because they do a lot of things, that good players would not do.

For instance fish might raise a hand like J♣T on a TXX flop, which a good player would never do.

And this is why to avoid making mistakes, we should often just fall back on game theory and call fish the right amount of the time.

Poker Hand Example #1 – The River Donk Bet

Pre-Flop: Hero is MP+1 with J♣ Q♠
3 players fold, Hero raises to 3BB, 2 players fold, SB calls 2.5BB, 1 fold

Flop: (7BB) Q Q K
SB checks, Hero bets 4.4BB, SB calls

Turn: (15.8BB) 9
SB checks, Hero bets $10BB, SB calls $10BB

River: (35.8BB) 8♣
SB bets 32BB, Hero call 32BB

This hand was played at 10NL on 888 poker recently.

On the river Villain decides to lead (donk bet) into me after calling me on the previous 3 streets. This is a bit strange given that only a few hands like Q8 or 88 improved on the river, and 88 seems somewhat unlikely, when he called both flop and turn.

I have no idea, what this guy is up to, and therefore I should simply attempt to call a certain percentage of the time, which with his sizing is around 50%.

I probably have some missed draws, and I also have worse made hands like AA or AK that I want to fold before this hand.

For that reason I should call with QJ, even if I am mostly only beating a bluff and not totally happy to face this big donk bet.

I should also lean towards calling, because my hand has some very useful blockers. When I have a Q in my hand, it is impossible for Villain to have QQ.

And he is only half as likely to have KQ, Q9, Q8 or AQ. He is also 25% less likely to have JT, because I have a J in my hand as well.

So even though my hand mostly only beats a bluff, it is still a much better hand to call with than for instance AK.

I did make the call, and Villain turned over 76♣. A good player would never get to the river with a hand like this, but bad players sometimes try to make a play without even considering their cards.

Or they have a lucky hand or other reasons, that are not logical. This makes them difficult to hand read, and sometimes our best option is to fall back on game theory.

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Poker Hand Example #2 – Size Matters

Pre-Flop: Hero is BTN with A 9
UTG calls 1BB, 5 players fold, Hero raises to 4.5BB, 2 players fold, UTG calls 3.5BB

Flop: (10.5BB) 5♣ Q 6 (2 players)
UTG bets 1BB, Hero raises to 6.4BB, UTG calls 5.4BB

Turn: (23.3BB) 8 (2 players)
UTG bets 1BB, Hero calls 1BB

River: ($2.53) T (2 players)
UTG bets 1BB, Hero calls 1BB

This hand was played at 10NL on PokerStars around 6 months ago.

I isolate a limper with A9, and on the flop he decides to lead (donk bet), but he chooses a completely silly size of just 1BB, which is the minimum bet.

I decide to basically ignore this and make my normal C-bet, like I would, if he had checked to me. He calls.

This is a concept that is discussed at length in Crushing in the Microstakes by the way.

And that is, minimum amount donk bets by a fish should simply be ignored. You should pretend their bet does not even exist and go ahead and make your standard continuation bet.

Anyways, on the turn he leads again (donk bet), and once again he bets the minimum, which is now an even more meaningless bet of less than 5% of the pot.

At this point however I don’t think I can get him to fold, and he will often have some weak pair like a 5 or a 6. So I just call getting plenty of odds to draw to a better pair than his.

On the river he again bets the minimum, and I still have just Ace high. At this point its tempting to fold, because it feels silly to call with Ace high and pay off a hand like 54 or K6.

But with this sizing I only need to be good 4% of the time to break even, and if I fold the best hand more than 4% of the time, I make bluffing profitable for him.

A9 high can beat most bluffs, and since I can essentially never fold a hand that might be good to such a small bet, I should call.

I did call, and he had KJ, so folding A9 would have been a mistake. A good player would never bet 4% of the pot with King high though, but bad players do it sometimes.

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Final Thoughts

In general we should not focus too much on game theory at the micro stakes.

However when we are facing aggression from very good or very bad players and we have no idea what they are up to, then we should understand the concept of MDF (Minimum Defence Frequency) and try to not deviate too much from it without a strong reason.

It is especially important, that we are not too inelastic. When we face a very small bet like in poker hand example #2 above, we should almost always call, if our hand might be good.

But if on the other hand it goes check-check to the river, and now suddenly out of nowhere a bad player bombs the pot with a huge overbet, it is equally important to not think, that he must be bluffing, and call too much.

Maybe he is bluffing now and then, but it’s more likely, he was trapping with a big hand, and now he is desperately trying to make up for lost value.

So we should mostly fold, and if he did indeed bluff us, then good for him. He is risking a lot of chips to win a very small pot, so this is not going to be profitable for him in the long run.

Lastly, if you want to know how to consistently make $1000 per month in low stakes poker games, make sure you grab a copy of my free poker cheat sheet.

I want to hear what you think though. What do you think about using GTO against bad players in low stakes poker games? Is this something that you do?


This article was written by contributor Lars "fundiver199" Kyhnau Hansen. Lars is a part time online poker player from Denmark currently playing 10NL and 25NL. Lars excels at the math side of the game.

GTO poker versus bad players


  1. Thanks as always, Nathan. In reference to Hand #2, in my experience online when facing the minimum c-bet (I call it a "lure bet"), I will typically call because it is a cheap way to see another card. The key is the river. If Villain hit his draw, or was trying to keep me in when he has a premium hand, the river bet will be big. If he missed, it will be small, so his hand announces itself.

    1. i think what's more frustrating is a fish limp call your overpair and flopped two pair or set minimum donk onto you. You value own yourself by putting him all in on river (assuming the board ran out safe)

    2. Aren't you concerned about losing value? If vilain misses on the river they might fold to anything. On the other hand, if you C-bet the flop and they have a gut-shot or back-door flush draw, then they're more likely to chase it. I'm still fairly new, but one of the first recommendations that's improved my game is getting my money in early when appropriate.

    3. Hey Morgan,

      I think in spots where a rec player bets the minimum they rarely have anything good. So I agree with the decision to just go ahead and ignore the bet and make a standard C-bet here.

      With that said, I think it can be ok to just call the minimum bet from time to time with some really weak draw. But overall, I prefer ignoring it and just making my standard C-bet.

  2. This is a great article, and it was applicable to a hand someone brought up to me recently. He declared that "the villain was a bad player so he'd never do what he did!" I said, "he's a bad player, so you don't know what he would do. You have to defend with good hands."


    1. I am glad this article helped! I agree, that is really the issue with bad players is trying to figure out what they will do next. There is often very little rhyme or reason behind their decision making.

  3. I agree with Morgan. The river bet size tells you whether Villain has been trapping you all along, or is just being weird.

    Although for a counter-example, I once saw a live player act like this when he flopped the nut flush. The pot had gotten big pre-flop and four people saw it, and Main Villain bet $5 into a pot of $60 after three diamonds came on the flop. The rest of us just looked at each other with the same "WTF?" look on our faces. Two of us called. Villain bet $5 again on the turn. At this point I folded, but someone else raised, and Villain called. On the river, which did not pair the board, he bet $10 into what was now a pot of about $150. The other opponent tanked for a bit, then called, and lost with two pair to the flopped nut flush. The bad player ended up leaving a few minutes later and admitted to the table he'd never played in a casino before, and had no idea what he was doing. We tried to be encouraging, but I think our strange looks made him feel a bit unwelcome. I hope he doesn't give up!

    1. This comment has been removed by the author.

    2. The alpha and omega of live low stakes.Never harass the fish,always be polite,always smile,always high five them and tell them nice play,and never ever ever make obvious that you are frustated after getting sucked out by a rediculus play.If you want to leave after such thing,its better to joke about it and say sth like,thats it for me,im saving the rest of my cash to buy me dinner,gas and wiskey or something of the sort.Or just say,its not my day,have a good night guys,and leave.Its essential to be known as a pleasant polite person in your local poker room.

    3. Hey Tarl,

      I agree that the river bet size often says a lot. Minimum bet is almost always a very weak hand or nothing at all.

      But sometimes a large full pot bet sizing on the river from a rec player can be a total bluff as we saw in the first example hand above.

      I actually think a half pot bet by a rec player on the river might be the real scary one haha!

  4. Hi Nathan,

    Great post here, definitely a concept that is rarely even identified, much less explained. I would like to add that trying to defend mdf typically results in defending hands with good blockers, which is a big winrate booster for players like me who previously would just overfold heavily. Another benefit is learning that fish/tight regs really do have enough/too many bluffs sometimes and bluffcatching them a bit more also increases your overall skill and profitability.

    1. Hey SD,

      Glad this article helped and thanks for your thoughts!

    2. hey nathan can you tell me how i can access your definitive guide to multi tabling video series

    3. Hey Bob,

      That was published many years ago on a poker training site I used to be an instructor at. I don't know if they still have it available.

  5. Nice article! I agree that playing GTO against bad players is usually not a very good idea.

    1. Thanks TJ! Glad you enjoyed this article.