Stars $20 Rebuy: Pocket 9's facing overshove

[Doylestown]

Villain is a complete unknown, just moved to my table. We're in the money, final 3 tables. What is your thought process here?

PokerStars No-Limit Hold'em Tourney, Big Blind is t1600 (8 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

BB (t88991)
UTG (t16022)
UTG+1 (t18806)
MP1 (t32361)
MP2 (t29695)
CO (t45936)
Hero (t32714)
SB (t43436)

Preflop: Hero is Button with 9[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/heart.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">UTG+1 raises to t18806</font>, <font color="#666666">[i]