preflop he has any 2, which makes it difficult.

i think the only hands he can call on the flop with a 9 are... J9, Q9, T9 and K9. 89 and A9 would be quite bad, anything else is just stupid.

of those hands on the turn J9 3bets you a bit, Q9 or a set almost certainly 3bets, T9 is played like this though because he still has the straight draw.

i think its pretty tough, but its a very thin value 3bet on the river.

(btw bet the turn)