AngusD switched from pro chess to poker two decades ago and has been professionally involved in the game on numerous levels since the very beginning of online poker, including playing as a poker ambassador both online and at major festivals around the globe. He has written much about the game over the years, and brings to YPD a wealth of experience in all aspects of the poker industry. Meanwhile, his many years on the pro chess circuit (he’s an International Master and prolific author) afford him an interesting perspective on the psychology of poker.

· Published 02.06.2021 · last updated 02.06.2021

One-card flush draws are simultaneously slightly appealing and potentially troublesome, particularly for inexperienced players. The problem is that we so often find ourselves with a starting hand such as K♦ Q♠ and, on seeing the Flop bring A♦ 8♦ 3♦, are not sure how to continue. It’s simply not a chance that we want to forego. The same goes when we have, say, A♦ T♥ on a J♥ 8♥ 5♦ 2♥ board. With three flush cards showing and one in our hand the incentive to continue is difficult to ignore. On the other hand, as opposed to the scenario in which the board features two flush cards and we have another two, in this case there are already made flushes possible which, of course, is an immediate red flag.

Not surprisingly, this is a situation that prompts many players to commit to unjustified, incorrect draws. Here’s an example: We’re on the Button with A♦ Q♠ and put in a pre-flop raise. We get calls from both Blinds and the Flop throws up K♦ 6♦ 2♦. It’s checked to us, we oblige with the planned Continuation Bet, the Small Blind wakes up with a check-raise and the Big Blind folds. And suddenly we’re in a tight spot! The most natural response for most players might well be to call for a few more chips because, after all, we’re sitting on the nut flush draw and with it the chance of picking up a juicy pot.

That may well prove to be the right move or a mistake, but we shouldn’t be making such an important decision without taking into account two key factors, namely pot odds and implied odds. If these and other considerations are not already part of your automatic thought processes, then perhaps you should start investigating and incorporating them. Starting with pot odds, a common mistake is the following line of thinking: using the so-called 4/2 rule we have roughly 36% equity (9 outs x 4), so as long as this is higher than the equity required due to the pot odds – let’s say that in this case it’s 25% – then we’re fine. However, this is a flawed analysis because it’s based on seeing the next two cards for free, and doesn’t differentiate in terms of whether we’ll face another (maybe untenable) bet on the Turn. The only way to approach this situation is to remember that this isn’t the final betting round. This means that if we were to face another bet on the Turn we’re in fact getting to see just one card, so instead of multiplying our outs by 4, the correct calculation would be 9 x 2. Given that this comes to only around 18% equity, calling this check-raise now looks totally unjustified.

What about implied odds? Well… even with a superior flush draw where the Flop has two of the relevant suit and we have the other two when the flush does hit it can be difficult to be paid off. Yet here there are already possible flushes on the board, and our opponent doesn’t have the magic Ace (or even the King), so should a fourth diamond appear the alarm bells will be ringing very loud indeed. If they have a flush of their own they’re very unlikely to dare commit too much, while a set is going to look less and less desirable with four flush cards showing. Therefore, however potentially promising this one-card flush might look, there’s more to suggest we save our chips than invest more. Having said that, if we think that our opponent is bluffing the Flop, and might well continue should a fourth diamond arrive, then in terms of implied odds there is a case for going along for the ride. The same goes for those players who can’t let go of a hand.


The above is a typical scenario from which we can conclude that, normally, calling would not be the best play. Of course, there are numerous considerations to take into account, and as well as folding, there’s also the option of 3-betting, too. As usual, it’s not an exact science but, generally, one-card flushes can be more trouble than they’re worth.

Good luck at the tables!

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