Ok. So it's down to heads up...here are the chip counts

hero: 4000
villain: 2000

blinds: 75-150

I'm in the SB with 5s 6s, and limp in, as usualy, the villain raise his 225 raise, and I call.

Flop comes down Kd, 2d, 3c (750)

villain checks, i check

turn is Jd

villain checks, I check

river 10s, villain bets 340 which smells of weakness to me. I raise him 800 more, and he calls and turns over J 4 offsuit...I was shocked by the call...was wondering what other people thought.

I think I like this play if the villain had bet the flop, or if the villain usually plays their draws aggressively rather than passively, and you have established a pattern of playing draws passively rather than aggressively.

As it stands, it's possible that the villain is just taking a bunch of free cards to complete his draws, and is attempting to extract some value on the river. A flush isn't folding to your river raise, and you'll probably get a "crying call" from a str8 there as well. So this is kind of a dangerous play since you can't discount a villain hand that can call what you are representing. Seems pretty dependent on a read of the villain and how he and you play draws.

Also, I think against a *thinking* opponent, it would probably be easier to bluff on the turn than on the river. The only hand that would be safe to check-behind and slow play the turn would be the nut flush, and a good opponent will realize that you would've probably raised preflop in a heads-up situation with an Ace. Any other made flush would likely bet the turn to protect his hand. Thus, it is harder to represent a flush on the river here. As for representing a str8, I think a thinking opponent would discount that as well, since a str8 wouldn't raise the river here, knowing that the only hand that calls his raise is the flush.

If your opponent isn't the thinking kind, then you shouldn't really bluff him anyways.

you were shocked that he called with second pair, after you tried to raise the river after showing no strength the entire hand, starting with the preflop limp??

His call is pretty standard here.

He is the thinking type. It took him over 5 minutes to make the call. I was trying to represent the flush but it didn't work. The reason is that we have a long long history playing heads up and we both know each other really well...The villain tries to make fancy plays all the time, and I didn't sense strength from his raise, I sensed weakness which is why I raised. He wouldn't be able to call me with anything but a top pair top kicker, or so i thought. but, i didn't put him on the king because he didn't protect his hand at all, the flush draw, didn't put him on that because he usually overbets his made draws after he completes them. As for the jack, I'd think that he'd bet the turn, but he didn't, that's why i was kinda confused.

I don't know if he put out a blocking bet to try to keep the pot small. Maybe he thought u called with a small pair and he was betting for value?