Thursday, 4 October 2012

The Post-Oak Bluff – An insight into post-flop play


The post-oak bluff was first introduced in poker legend Doyle Brunson’s Super System back in 1979. It is defined as “a very small bet relative to the size of the already-existing pot and may be employed as an attempt at using reverse psychology to steal the pot”.

In his book, the legend brands this as a “gutless” and “weak” play insisting it’s one he would never make. I may be no legend but I beg to differ with the godfather of poker on this one and think this is a great weapon to have in your arsenal. I had a hand come up recently I thought was a legitimate spot to execute this play so hopefully the following example with my analysis is enough to prove the big man wrong!

Hand played on Pokerstars
Seat 5 is the button
Seat 1: Player 2 ( $2140.00 USD )
Seat 2: Hero ( $1635.00 USD )
Seat 3: Player 3 ( $1760.00 USD )
Seat 4: Villain ( $1435.00 USD )
Seat 5: Player 4 ( $650.00 USD )
Seat 6: Player 5 ( $1380.00 USD )
Player 5 posts small blind [$10.00 USD].
Player 2 posts big blind [$20.00 USD].
** Dealing down cards **
Dealt to Hero [  Jd Td ]
Hero raises [$60.00 USD]
Player 3 folds
Villain calls [$60.00 USD]
Player 4 calls [$60.00 USD]
Player 5 folds
Player 2 folds
** Dealing Flop ** [ 6s, 3d, 4d ]
Hero bets [$125.00 USD]
Villain calls [$125.00 USD]
Player 4 folds
** Dealing Turn ** [ 2s ]
Hero bets [$280.00 USD]
Villain calls [$280.00 USD]
** Dealing River ** [ 2h ]
Hero bets [$262.00 USD]
Villain folds
Hero wins $262.00 USD
Hero wins $1020.00 USD from main pot

Before discussing the merit of the post-oak bluff which is on the river in this hand, I’ll talk through each betting round as they occurred.


So I’m dealt 10-J suited UTG 6 handed and it’s early on in the SNG. A lot of good players will fold and I definitely couldn’t fault that. However, occasionally I like to open hands like these from EP to balance my range – if I’m only opening around the top 5% of hands or so from EP I can never expect to get paid off with my big hands against a good player who is observant and looking at opening %s from various positions. J-10 suited is the kind of hand you want to balance your range with since it plays so well post-flop, unlike something like A-8o/A-7o which is dominated so much more of the time when called and doesn’t flop as well.

So I have two callers and it looks like I’ll be playing out of position post-flop.

FLOP: 6s-3d-4d

So it’s a pretty good flop for me, I’ve got two overcards and a flush draw giving me a total of 15 outs with two cards to come. This will give me around 55% equity in the hand assuming all of my outs are good. My overcards of course may not be good but betting will make them good in some instances where A-J/K-J/A-10 may fold as I'm blocking those potential flush draws. Since this is a pretty innocent flop and has likely missed both opponent’s ranges along with the fact I have the initiative in the hand having raised pre-flop it’s definitely a spot to lead. Besides, check-calling would typically look like a draw since I’m the one that opened the hand pre-flop and the norm is to c-bet. I lead for a little over half pot at 125 into 210 and receive one caller. I’m not really in tears about this given how much equity I have and if the caller is a fish then I’m just building my own implied odds with the bet and ensuring maximum value in the final betting round if I hit.

Villain has a VPIP of 61% and AF of 1.0 – granted over only 18 hands these numbers are pretty meaningless but they do suggest he will be a loose-passive player. This means it won’t be as tough playing out of position in future rounds since we won’t expect villain to utilise his positional advantage and aggress all that much. It also means we can expect his calling range on this innocent board to be pretty wide.

What kind of range am I assigning villain?

When he calls I’m expecting a lot of overcards that have missed entirely, he may even have some flush draws (better or worse) too and pairs that have hit sets on this board as well as A-x pairs on the board. Again, granted his VPIP % is only based on a very small sample so is by no means a true reflection but it’s all the information we have so it’s all we can go by. So it’s off to the turn…

TURN: 2s

Shit, the straight’s came, time to check and hopefully get to a free river? No…A lot of people will check here and I think it’s a mistake. His VPIP is 61% so we’re expecting him to have a shit load of hands he’s called with on the flop; hands that have a 5 in it only constitute a very small part of that range – 5s/A-5o/A-5s so I’m not overly worried. You might also think with his high VPIP why bet the turn if he’s loose and likely to call again? With the equity our hand still has we would be able to check-call most bets up to pot, so if your hand is worth check-calling a bet it’s usually best betting yourself since it offers the opportunity of winning immediately which check-calling doesn’t. And again, if he calls we are continuing to build our own implied odds and giving ourselves the best chance of maximum payoff on the river should we hit.

So, I opt for a bet of little over half pot again, 280 into 460, and he calls. There’s now 1020 chips in the middle and it’s off to the river.


So the river pairs the board and we have missed our hand. The 2 makes it much less likely 2s/A-2 is in his range. Nonetheless, I’m expecting him to call the turn with the majority of hands he called the flop with – he may toss some overcards on the turn like K-Q/Q-J/J-10 but it’s really tough to know. More importantly, I’ve missed my hand, I’m OOP and the action is on me…Spot to give up and check or spot to bluff, and if so, how much?

Flopzilla analysis

Firstly, to look into the merits of whether this is a legitimate spot to bluff or not, I’ve looked at the situation in a piece of software called Flopzilla. This allows you to develop insight into how certain ranges hit certain boards and will show you in what ways and how often that range hits that board. Obviously the reliability of its data is entirely dependent on your subjective estimation of your opponent’s hand range, but hey, thinking about ranges is better than not thinking about ranges even if you’re completely wrong and is a skill that can be developed over time.

In this hand, I have assigned villain a subjective range of hands which constitute 24.7% of cards – this includes: 2s-7s/A-2o-A-Ko/A-2s-Aks and some middle ranked suited hands and some overcards like K-Qo/K-Jo. So, when comparing this range to the board and this is where flopzilla comes in, 39.4% of the time he will have A high and 29.5% of the time he will have complete air – combined that’s 68.9%. If we stick in a bet of 262 into the pot of 1020, we’ll only have to win the pot around 1 in 6 times to show immediate profit. Basically, we only need him to be folding as little as 16.66% of the time or more to win money and with the fact he’ll have a nothing-hand 68.9% of the time based on our subjective assignment of his hand range, then it clearly makes it a profitable spot to lead for a post-oak bluff. Okay, he may call with A high meaning we might only win at 29.5% at worst (and even then it’s still a profitable bet) but it’s also our fourth barrel in the hand so I wouldn’t count on it. To some opponent’s it will really look like a luring bet as well that’s crying out “call me” so folding A high definitely wouldn’t be unreasonable.

So, 262 into 1020 I lead and villain folds, BoOooOOooOoMmm – profit!!
Notice that my river bet was smaller than the turn bet.

So what’s so good about the post-oak bluff? Why is a small bet the best in this example?

Aside from the fact we have to win the pot so little of the time to profit (and infact, we could afford to lose our next 5 bluffs in this exact same spot and still break-even) I am not expecting villain to fold any of his range that has connected with this board to ANY bet size (hands such as sets, overpairs, straights and one pair A-x hands). if this is true and along with the fact that the times he has complete air and can’t call any bet whether it’s full pot or 1/5th of pot then it only makes sense to bet a tiny amount so you are losing less chips the times you are called when you run into those made hands in his range. Besides, with this guy’s high VPIP I’m not expecting him to fold even A-3 or A-4 so there’s no incentive to increase the size of our bluff if simply all his made hands will call and all his air hands will fold. It may sound fairly contradictory talking about building our own implied odds on the turn for a potentially big river pay-off against a player with a high VPIP and then going on to bluff him, but given that he will still have a shit load of nothing a high % of the time it actually makes perfect sense.

You often see player’s betting 80%/90% of pot because it “looks stronger” or is “more likely to induce folds” or because they don’t really know and aren’t thinking about ranges, but if your bet is targeted at folding out a portion of your opponent’s range that can’t call any bet then you should be thinking about risking the minimum and saving yourself some chips and $ in the long run.  

And Doyle branded this a "weak" and "gutless" play...*tut tut*...Back to school methinks!



  1. you are better than Doyle IMO, people should follow your blog!

  2. TY TY!!

    Doyle sucks anyway, always folds A-Q cause "it's a rubbish hand", LOLOL NICE REASONING MATE! NICE FOLD IN TODAY'S GAMES WHERE PEOPLE OPEN 8-3o UTG!!