Pittsburgh took two of three from the defending NL champions and has won five of seven overall. St. Louis (71-61) leads the NL wild-card race, with San Francisco (69-62) trailing by 1 1/2 games and the Pirates (69-64) one game back of the Giants for the second wild-card berth.
Davis hit his 10th homer in the second after Wainwright hit Russell Martin on the left elbow with a pitch that Martin barely tried to avoid. Davis sent an 88 mph pitch clanking off a speaker raised on a pole, about 15 feet above the seats, a drive estimated at about 433 feet. A night earlier, Davis had a pinch-hit, tiebreaking, three-run homer in the eighth inning of Pittsburgh's 5-2 win.
Davis also had an inning-ending lineout that left the bases loaded in the fifth.
