Today I want to discuss a play that is underutilized by no limit hold'em players. Rest assured, plenty of players use it and understand it, but for those who do not, which is most, you can use it quite effectively.
What is a blocking bet? Typically it is a bet that one makes on the river to block a bigger bet by your opponent. Thus you make the blocking bet when out of position; that is, when you are not last to act. Blocking bets make you money, by losing less than you would have. For example, if you bet one-fourth of the pot on the river and your opponent just calls with the better hand then you save money if your opponent would have bet half the pot, say and you would have called that amount. Essentially, you are looking for a cheap show down. The blocking bet is also used to discourage a bluff by an opponent. Checking shows weakness, and this induces bluffs. Betting indicates strength and opponents typically do not raise when they sense strength unless they have a very strong hand themselves.
Obviously you do not want to make a blocking bet with a great hand. You want to bet your hand for value in such cases. A good candidate for a blocking bet is something like top pair with an okay kicker. For example, you are playing 1/2 NL and have in the BB and are heads up with another player. The board reads: . You have top pair, but it certainly isn't a great hand. The turn and river cards look pretty safe and if your opponent was slow playing a hand like then you just caught up. Nevertheless, your nine kicker is nothing to get excited about, since lots of better tens are possible. You could also be dead to a flopped straight but the paired board should cause some worry to the opponent and moreover, if you lead here, a player with a straight is unlikely to come over the top now that the straight is no longer the nuts.
Let's say the pot is $44, with you having bet on the flop and turn with only this other player calling. A $10 bet on the river qualifies as a blocking bet. A player with a hand like may conclude that he/she now holds the best hand if you check the river and consequently fire a $15-$20 value bet. Moreover, a check may induce a bluff from a busted flush draw. If you check and your opponent bets $30, you have a very difficult decision to make. By betting, you create a situation in which a raise from your opponent carries much more weight. It takes a lot of courage (or foolishness) to come over the top with a busted draw or just a lone pair on the river. Your bet blocks your opponent from exploiting your weakness.
The bet also can make you money by garnering calls from weaker hands that would fold to a larger bet or just check behind. In our example, a hand like will likely call a $10 bet in a $44 pot. That's not to say it's a great call, but if your opponent has come with you this far in the pot with a hand like that, then a small bet will probably get called too. A hand like will almost surely call from sheer frustration, having missed all 17 outs.
Another situation in which the blocking bet is useful is when a scare card hits the river. A scare card could be a card that completes the flush or straight draw or just a high card like an ace. For example, you have K-K and have lead a Q high flop and a safe turn card, but now an Ace hits the river. A check may induce a bluff from an astute opponent, who can infer that after raising preflop and leading the flop and turn a check on the river likely means that you aren't happy to see the ace. A check induces a bluff whereas a bet discourages it.
If you lead the river and your opponent comes over the top, you have a much better idea of what sort of hand your opponent has. It is unlikely that your opponent called you down with merely ace high, so it is more likely that your opponent has aces up or has slow played a set and you can fold in pretty good conscience.
Consider a case in which a flush card hits in a contested pot. You have in the CO (cut off), lead the flop and called the button's raise on a board of . Let's say the turn brought a and the river now brings a . Let's say you both checked on the turn. You could check here, but that indicates weakness and your opponent with a Q-J may just put out a half pot bet that will put you to a difficult decision. You can prevent this bluff by making a blocking bet. A hand like will rightly conclude from your check that you do not have the flush and so will make a normal value bet, which will also give you a difficult decision. The smaller blocking bet also has a better chance of being called by a hand like Q-J or J-T, though passive opponents will probably check behind on the river with such hands.
Let's consider one final example. You have in the BB. You flop a flush draw and a MP (middle position) limper bets half the pot which is called by the button and you. Everyone checks the turn and the river completes the flush. You have a strong hand but not great. Unless one of the players has the nut flush, a bet is unlikely to be raised. A smaller bet may also earn a call by a weak hand like top pair depending on the player. As in the previous examples, you are hoping for a cheaper showdown than you might get if you check and allow the better hand to bet cold. If the button has and everyone checks to him/her on the river, a bet of more than one-quarter of the pot is surely forthcoming. If you make the blocking bet, however, the button will fear the nut flush and only call.
Now that we have some possible situations before us, I want to introduce a final variable. As with all poker plays, you must use the blocking bet selectively. There is little point in putting out a blocking bet against a calling station. Just bet your hand for value. The calling station will call with all sorts of hands that you have beat, so go ahead and make a good-sized value bet.
Similarly there is little point in putting out a blocking bet against a passive player. This player is unlikely to bluff you on the river or to make a thin value bet. If you think there is a real chance that you are behind then check. This player will let you know if you are up against a good hand.
Another player that I would not waste a blocking bet on is the weak-tight player. This player is usually just as scared of the river flush card as you are. Either bluff that card and push the weak-tight player out or check as the weak-tight player is only betting with the flush.
At the opposite end of the spectrum is the basic loose aggressive player who will pounce on river weakness. Checking induces a bluff. If you have a strong hand then this player is a good candidate for check-raising the river, but with a vulnerable holding a bet on the river discourages a bluff that you may not want to try and pick off.
Finally the basic tight aggressive opponent is another candidate to try this play on. Checking may indicate to this player that you are not happy with your hand, and this can result in a value bet larger than what you could have paid for the showdown. Again, the purpose of the blocking bet is to lose less money than you would otherwise lose by checking and calling a bet. As with the loose aggressive opponent if you check the river scare card, an astute tight aggressive opponent may attempt to push you off your hand. Good luck!