O'Brien secured the save Thursday against the Reds, allowing no runs on one hit and two walks in one-third of an inning.
O'Brien needed just one out to finish it off for the Cardinals but made things very interesting, allowing two inherited runners to come across before getting Matt McLain to line out sharply to right field. The All-Star right-hander gave up his first hit since Aug. 2 in Toronto, so his grip on the Cardinals' closer role remains strong. Through 52 innings, O'Brien sports a 2.94 ERA, 1.12 WHIP and 53:22 K:BB with a league-leading 33 saves in 38 attempts.