[d240t]

I wouldn't fold this river to any bet either.

It is possible your opponent has a "worse" 9 - which unfortunately is a chopping 9. But it is also possible he did not believe you had a 9 on the flop (the tendency in low buy-in tourneys is for people to slow play it). Once he checks the river, you should be almost positive you have the best hand (I am) and you should clearly bet.

My analysis would repeat Nath's, except I'd include the possibility of many hands that aren't as good - slowplay bluffs from the flop and middle pairs that protected against a possible flop bluff by betting the turn.

If I was your opponent (which I wasn't), I'd be likely to have a wide range of hands after check-calling a late position bet in a multiway pot on a paired board and betting out the turn, including many bluffs and semi-bluffs. But if I checked that river, I would almost never have a hand that beats you outright.

Oh...and I'd be even more sure you are ahead if you have been losing a lot lately (as your cold-decked comment indicates). You losing a lot lately may give you the image of a fish, indicating he is less likely to believe your flop bet indicates a 9.