check the flop, call down.

[Trix]

The river is an easy raise, I dont see how you can rule out any made hand that doesn´t beat you. He probably puts you on 77 or something like that when you call the turn, so when you raise the river he will often call out of confusion. Heck, he probably sometimes tiltcall the 54 he held if you give him the chance of making the mistake.