Pro concepts: Isolating weaker players

There’s a lot of talk in poker about sharks and fish. The whole aim of the game is to become a good player (shark) so that you can eat up the bank balances of the bad players (fish). However, just like in the ocean there are only so many fish swimming around to satisfy all of the sharks, so how can we ensure it’s us getting fed and not somebody else?

The answer is by isolating the fish preflop. Winning is so much easier when you have the fish all to yourself, and isolating them preflop is the easiest way to achieve this. Once you have a fish heads-up in a pot you are the one in control of how big the pot will get, how many streets you want to bet and when to shut down. Your decisions will all be easy, and it will be difficult to ever lose big pots. Well-timed isolation raises will gain you a lot of money in the long run.

Perfect isolation

An isolation raise can happen in one of two main ways. The first, and most common, situation occurs when a known weaker player limps preflop. In a typical six-max cash game, the fact a player is limping in should instantly tip you off that the player in question is probably a fish.

While it may be more common in tournaments and full ring poker, it is rare for good players to limp in six-max cash. Although you should try to back up your assumptions with more solid reads before you label someone a fish, as soon as a player limps the whole table will be on standby to try and steal his money.

If you’re on the button or cutoff with a half-decent hand following a limp (I’d go as low as 8-7 offsuit on some tables) you should make a larger than usual preflop raise to fi ve big blinds. This is designed for a few reasons. It will either fold out the players left to act and pick up a small pot right away, or you will play a heads-up pot in position versus a poor player who is likely to have a weak range. In a sense, your hand doesn’t really matter as you’ll be playing more against his weak range and the board texture than your absolute hand strength.

If the fish calls you should be looking to continuation bet most flops. The perfect flops to bet are uncoordinated ones with an Ace or King in them such as 2-6-K rainbow or A-7-3. Your opponents will rarely have an Ace or King in their hand as they would have raised preflop if they did, whereas they can quite easily put you on top pair.

In fact, the only fl ops I would hesitate to continuation bet with air are ones such as Q-J-7 or 6-7-8. A fish’s limp-calling range seems to be made up primarily of hands like Q-J, Q-T, 9-7 that all hit these boards quite well. It’s better to check back here and bluff the turn instead if you’re checked to a second time. Winning these small pots over and over again will quickly add up to a very profitable win rate.

Reraise it up

The second form of isolation-raising is to make a small three-bet in position after a fish has raised preflop. This carries more risk, because the pot size will be larger, but the rewards can also be greater. Let’s say a fish raises to 3BB from the cutoff and you have K-J on the button.

Standard practice may be just to call and play a small pot in position versus a fish. While this isn’t a bad line you are inviting aggressive players in the blinds to squeeze or enter the pot, which minimises your chances of winning.

An alternative play is to three-bet to 6-7BBs with the sole intention of getting the pot heads-up. Your hand is nearly good enough to three-bet for value, and with the benefit of position, and our superior hand reading skills, we can still expect it to be very profitable. Again, you can now dictate how many bets you want to put in postflop as you are the aggressor.

Most fish are very rarely going to fold any of their range to a small three-bet so you have to be comfortable playing postflop to try this. Obviously, if you are four-bet by the fish you can make a simple fold. If in this situation you hold a monster hand like A-A I’d advise you to revert your three-bet size to a more normal 9-10BBs. With a big hand you want to inflate the pot against an opponent who is a calling station.

Beware that this bet sizing is totally exploitable from aggressive opponents yet to act.  However, the amount of times you will actually be exploited in practise is fairly low. Keep using this tactic until you are given a reason not to by the other thinking players at the table.

Exploit the exploiters

It’s important to remember that you won’t be the only player at the table looking to exploit the fish. Now that we know how it’s done we can begin to punish those who dare to attempt isolation raises of their own. When you see a fish limp and a good reg isolate from the button you should be three-bet bluffing a very wide range from the blinds. You know that the fish isn’t going to call much, and there’s a really high likelihood that the raiser will fold, so you can win an easy 7BB pot.

Your three-bet size should be to around 16-17BBs in this spot. As this is inflated from a standard three-bet size you’re unlikely to be flat called as much (assuming the relative stack size is around 100BBs).

Calling with hands like 7-7 and K-J now becomes quite unprofitable for the raiser because he will be investing a big chunk of his stack before folding to continuation bets on many flops. As such, you are likely to either win the pot there and then or the original raiser will four-bet.

This is actually another bonus for us as our positional disadvantage is now alleviated entirely. Generally you should just fold your light three-bets to a reraise, but it’s important to sometimes get involved in a levelling war. This can lead to some interesting all-in hands that can look very loose out of context. Just as you know that he was isolating light, he knows that you are three-betting light and will thus sometimes be four-betting light.

When you believe your opponent is capable of making these assumptions you must five-bet all-in over the top with air occasionally. In this specific situation you need to be shoving a much wider range for value too, and this could include hands such as 88+ and A-Ts+.

If you can find the right balance between isolating fish and exploiting opponents who are attempting the same trick then you will have mastered one of the key skills of cash game poker. Suddenly the ocean you were previously in, with multiple sharks chasing after only a handful of fish, will be more akin to dinner time for one hungry Great White on a feeding frenzy.

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