mASSIVE OVERBET

[greywolf]

1/2€ NL holdem at 24hpoker flop comes down 457 all in clubs and i flopp top set 777 theres 20 in the pot after my preflop raise and we were three to see the flop with me on the virtual button. Player 1 checks and Player two immedieately push for 400, a cute little overbet.
Whats your move? i folded but dont think that was the best thing to do. he could very well have the lone ace of clubs,