Man, I'm a spewer in HU. If villian had a PP worth playing, he'd 3 bet the flop unless he decided to slowplay a monster like AA, so I don't think he has a set. I put him on a OC's with one high flush card or a made flush. So you're either beat or vulnerable to 15 outs, plus the chance he has a set, some big OP, or A9s makes me think 4.5:1 isn't worth calling down.