What's his hand?

[Mackas]

150euro rebuy live tournament. Rebuy period is over about one and a half hours. I have T5200, reckon ave stack is about T8000 - T10000 but blinds are only 150/300. I have been playing relatively tight as was getting very little cards and table was a bit wild during rebuy period (surprise surprise). However in the last 30 mins since play has slowed down a bit I have raised 1200 to take the blinds from middle to late position three times.

Folded to me with KTspades 2 from button. SB and BB have both been playing tight although BB has called a couple of times with speculative (and sometimes dubious) hands in BB to what he may perhaps perceive as a steal. Otherwise he has played quite conservatively and cautiously even when he misses flop after calling a raise in BB. He has maybe T2000 more than me. It is folded to the BB who calls and we're heads up.

Flop is Ad9s8s and there is T2550 in the pot. He goes all in. I have a flush draw, and backdoor str8 draw, think about it and fold - the blinds are still low enough and I have a playable stack remaining.

I did however find his bet very odd. If he has a monster (trips, two pair?) he would probably check and hope I bet it for him. If he has a weak ace why not check and call as by betting he is possibly only going to be called by a hand that is beating him (ie a bigger ace). Ditto if he has hit the 8 or 9. If he has a weaker PP he should have reraised preflop if he thought I was stealing rather than waiting for an Ace to fall. Which leaves the possibility of a bluff or semibluff. I dont think he was bluffing completely as taht runs contrary to how I saw him play for four hours or so before that. Did he have JT for an openended str8 or possibly even two spades as well, maybe even small suited Ace spades?

Anyway I've been thinking about this all day and would appreciate someone else's thoughts. Obviously there is no correct answer as he didn't show but what would you guys think?