live 2-4: show my ace?

[pete fabrizio]

$10 straddle on the button. one limper, I make it $45 in cutoff+1 with A9s. cutoff calls. sb is a tight/weak player who labors forever and i think mutters something about being "dominated" and then calls. bb folds, button straddler calls, limper folds.

Flop A84r, checked around. Turn T, putting out two diamonds. SB thinks for like 15 seconds and checks. I bet $125, cutoff and button fold. SB tanks and can't seem to make up his mind. He has about $200 behind. I show him my ace, and he folds.