The semi-bluff

A semi-bluff is a bet or raise with a hand that is almost certainly not the best right now, but could still become it. Think of four cards of one suit or an open-ended straight draw. You bluff, with a safety net underneath: if everybody folds, you win now; if somebody calls, the next card can still make you the winner. Two ways to win in one move, and that is exactly what makes the semi-bluff so much stronger than the pure bluff.

The arithmetic behind the safety net

Take a flush draw after the flop: nine cards complete your flush, and with the rule of 2 and 4 that is roughly 36 percent through to the river. How you count those chances is in counting outs. On its own, 36 percent is not enough to pay big bets. The semi-bluff turns the sum around: you do not need a 50 percent chance of winning if your opponent also folds regularly. If he folds three times in ten, your safety net only has to catch part of the rest to make the move profitable. Fold chance plus win chance is the sum that counts.

A concrete example makes it tangible. In a pot of $10 you bet $6 with your flush draw. If your opponent folds a third of the time, that alone earns an average of $3.33 in direct profit. In the other cases you play a bigger pot in which you still make the best hand roughly one time in three. Add those two sources together and the bet more than pays for itself, while calling passively with the same hand makes it a marginal gamble.

Which hands lend themselves to a semi-bluff

The stronger the chance of improving, the more aggressive you may be. The top: a flush draw plus a straight draw, together good for fifteen outs, which makes you the favourite even against a single pair. After that the flush draw with nine outs and the open-ended straight draw with eight. At the bottom dangle the gutshot with four outs and loose high cards: with those you semi-bluff at most occasionally, in small pots. What your chance of winning is worth against your opponent's hand you can read in what is equity.

How to carry it out

With the initiative the execution is obvious: you raised before the flop, you have a draw, so you simply carry on as if the flop suited you perfectly. That follow up bet, the c-bet, gets exactly the bluffs it needs from your draws; see the c-bet explained. Without the initiative the check-raise with your best draws is the aggressive alternative. Pick a normal bet size, the same one you would choose with your strong hands. A conspicuously small or panicky large amount tells attentive opponents exactly what you are doing. Think a street ahead as well: choose before you bet which turns you carry on with and which you do not. On cards that strengthen your draws or your story you keep pressing, on scary cards you check back. That way you avoid having to start thinking all over again on the turn while the pot is already big.

The traps

Three mistakes make semi-bluffing more expensive than it needs to be. One: playing every draw aggressively every time, which runs you into raises with hands that would rather have looked cheaply. Two: semi-bluffing against players who never fold; against a calling station the fold chance disappears and only your 36 percent is left. Three: carrying on firing on the river when your card has not come, with no plan. The semi-bluff is strong because on the flop and turn it has two ways out; on the river the safety net is gone and other rules apply. So decide in advance: if you miss, you check or give up, unless you have a considered bluffing plan.