99 with board Overcards

[Boggy Depot]

"grunch"

Check the river, call villian's bet if you want. I doubt he has a 4 since he should have check-raised on the turn to avoid flush/straight suck-outs (though he may still have it). After the river there are flush/straight possibilities, and three overcards. If villian hit any of it, he's staying and has you beat. He may be playing 8-8 or 7-7 but as is, I'd place villian with Ace/weak kicker.