[nut case ace]

Yeah, the river bet is no good. The reason is that when he capped, he most likely had a pair or AK. If you have reason to believe otherwise, then that's the kind of stuff you need to add to your post, otherwise we'll assume he's an average player who doesn't cap in this situation with anything less than AK. Anyway, on the river, the bet accomplishes nothing for the following reasons: if he has some sort of garbage, he's probably not going to call, and if he decides to play then he's most likely going to raise trying to push you off a weak hand (like AK) and then if you're still convinced you have the best hand you have to put in another big bet. You want to put in as few bets as possible with a hand like this on the river. Conversely, if he has a better hand, he's going to call with it, or raise when he has a really good hand, and in both cases you lose at least one bet. Basically, the most likely scenarios given the pre-river action are that you are either going to bet and not get called or bet and get called by a better hand. So when you win, you don't gain an extra bet, and when you lose, you lose an extra bet. Sorry, that took way too long to explain, but if you understand it, it will save you a lot of money.

So, what to do? Just check, and if he bets and you really think you have the best hand, call. If you don't like this line because you think you're losing value by not betting, reread the whole first paragraph. I hope this makes sense.