Zack hit his flop perfectly and has an ace-high flush. Being in first position he simply checks. He gets two more checks followed by a pot bet by Brian on the button. Zack is the only caller. On the turn Zack suspects that given the opportunity Brian will bet again, so he checks. Brian unfortunately checks in response. The river comes and is likely of no use to Brian. Zack thus makes a small value bet, Brian calls, and Zack takes down the pot.