Chapman came on in the ninth inning of Saturday's National League Central-clinching win against the Dodgers and closed out the victory in just three batters.
The Cuban southpaw got Matt Kemp to ground out to first to start the inning. He walked Adrian Gonzalez on five pitches before getting Hanley Ramirez to ground into a game-ending 4-6-3 double play.
After some deliberation with pitching coach Bryan Price, acting manager Chris Speier said before Saturday's game that Chapman would be available to pitch, but he likely would not close.
It wasn't a save situation by definition, but the pressure was certainly on with the division title on the line. But Chapman answered throwing as hard as 99 mph and tossing seven of his 12 pitches for strikes to secure the win.
The Reds shut down Chapman after his Sept. 10 outing against the Pirates when he could not finish an inning for the first time all season. They diagnosed their hard-throwing reliever with fatigue in his left arm and have rested him since then.