playing in a £50 rebuy last night, just got back after the break and i have 25k chips ( avg 9k) and i am chip leader on the table by 6k ish
blinds are 300/600
UTG + 1 raises to 2100 (this guy has 18k chips and has only recently moved to the table)
im next to act and look down at  
 
 i re-raise to 6k total 
he thinks for a min or two and flat calls, and checks the flop blind 
 
 
 i check behind
turn  

he now shoves and says *we'll see where were at then*  its 12k for me to call and if i call and lose im down to 7k
what do you do here ??