Whenever you make an offensive move in Holdem, you should know why you’re making it. Many players choose to raise or bet on instinct alone, without really considering why they’re doing what they’re doing. This is a big leak for them, and something you want to exploit.
One reason to make an aggressive move is to isolate a player. When we talk about isolation, we’re talking about making a preflop raise aimed at pulling a specific opponent into the pot alone. Isolation bets are a great way to punish terrible players and to get paid off easily. Isolation is a great justification for aggression.
Let’s investigate further.
Why Isolate Opponents Preflop?
Isolating specific players preflop is a great strategy because it focuses your game. In Holdem, the idea is to play against the worst players as often as possible. If you can create situations in which you’re playing only against bad players, your profits will increase.
In essence, this is exactly what isolating preflop does – it ensures that you’ll be playing a pot against a player on whom you’ve got some sort of advantage. The more pots you play against poor players, the more money you win.
When to Isolate Opponents Preflop
Say you notice a player sitting ahead of you who likes to limp under the gun when you’re on the button. Limping under the gun is a terrible move, so you can deduce that the player UTG is a bad player in general. You can and should exploit this by isolating him whenever you can.
Imagine you’re dealt 79s on the button. UTG limps in, a weak-tight player behind him limps, and the action is on you. Should you call, raise, or fold?
This is a perfect opportunity to isolate the player under the gun. You’d love to play a pot with him for two reasons: first, you’ve got position; second, you can easily outplay him postflop. While 79s isn’t a great hand in itself, its value increases significantly in a pot against a bad player and in position.
In all likelihood the player under the gun will call your raise and the player behind him will fold. The flop will come rags and you will both miss. Your opponent will check to you, you will fire a bet, and he will fold. Easy money unless he’s a calling station. In that case, all you have to do is isolate him with a slightly narrower range and value bet him to death.
That’s the power of isolation.
Isolating Opponents in Position
The most common situation where you’ll want to isolate is the one we examined above, when you’re on the button and a weak player ahead of you limps preflop. Limping preflop is almost always a terrible move, so we assume that consistent preflop limpers are bad players. We want to play hands against bad players in position, so we isolate preflop. Pretty simple.
You’ll also want to isolate limpers when you’re in the cutoff seat and the player on the button is weak-tight. In a situation like this your isolation bet is unlikely to be met with any resistance, so it’s almost exactly like isolating from the button.
You need to be more careful when attempting to isolate from middle position. There are players behind you, and if any of them are aggressive you will most likely be found out and punished. Here it’s a matter of adaptation. If they figure you out, you adjust your game, and so on. But it’s much easier to isolate from middle position when players to your left aren’t going to put up a fight.
Under the gun is a different animal altogether. When you’re under the gun, the only players you can isolate are the blinds. It can be profitable to isolate the blinds from under the gun, but it’s tricky to pull off. Since you act first preflop, you don’t get to see if either the small blind or the big blind limps beforehand; so you’ll want to make sure you have very strong reads on both players before raising.
If you know that one of the two blinds is a calling station, you can isolate every now and then. The players behind you will generally put you at the top of your range, since you’re in the worst position at the table; thus you’ll meet little resistance and get to play a pot with a fish.