''It's the first time he's been involved in games that have this kind of significance this late in the season,'' Pirates manager Clint Hurdle said Wednesday after Davis' long home run keyed a 3-1 win over the St. Louis Cardinals. ''He's showing up to the ballpark ready contribute any way he can.''
Davis hit a two-run drive off a speaker above the seats in right-center field in the second inning. A day earlier, Davis had a pinch-hit, tiebreaking, three-run homer in the eighth inning of Pittsburgh's 5-2 win.
Davis arrived in the major leagues with the New York Mets in 2010 and was traded to Pittsburgh in April. The Mets finished with losing records in all of his seasons in New York.
''It's hard when you're mathematically eliminated,' Davis said. ''You hit a home run and it's a great feeling still, but it's kind of like it didn't really matter. If you're still in it, it definitely feels a little sweeter.''
Davis hit his 10th homer after Adam Wainwright (15-9) plunked Russell Martin on the left elbow with a pitch that Martin barely tried to avoid. Davis sent an 88 mph cutter clanking off a speaker raised on a pole, about 15 feet above the seats, a drive estimated at about 433 feet.
''I just got the barrel on it,'' Davis said. ''It just carried out today.''
Wainwright knew he made a mistake when he saw where his pitch was headed.
''I threw it right into Ike's swing path, and he made a good swing on it,'' Wainwright said. ''I wanted to get the pitch higher, but I got it and down and in, and that's a left-handed hitter's honey spot right there.''
Davis also had an inning-ending lineout that left the bases loaded in the fifth.
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.
Jeff Locke (6-3) allowed one run and six hits in 7 1-3 innings, giving up Matt Holliday's third-inning homer. Locke also singled in the third and scored on Andrew McCutchen's sacrifice fly, just the 11th hit for the pitcher in 98 career at-bats.
Mark Melancon pitched a one-hit ninth for his 24th save in 28 chances.
Locke escaped trouble in the third, stranding Daniel Descalso on third when Josh Harrison made a diving stop on Randal Grichuk's two-out grounder down the line and threw to first
Wainwright allowed three runs and eight hits in six innings. He gave up five runs to Philadelphia on Aug. 22 and has gone winless in consecutive starts for just the second time this season.
''Yo'ure not going to be at your best all time,'' Cardinals manager Mike Matheny said. ''Right now, he's not at his best, but he showed some good signs today.''
C Yadier Molina was to begin an injury rehab assignment and catch five innings for Double-A Springfield on Wednesday and could return to the Cardinals on Friday. He has been on the 15-day DL since July 10 because of a torn ligament in his right thumb. ... RHP Michael Wacha was to throw a batting practice session before Springfield's game Wednesday. A right shoulder stress reaction landed Wacha on the DL on June 18.
3B Pedro Alvarez was out of the lineup, a day after he was removed from a game due to left foot discomfort. Alvarez left PNC Park with a walking boot on his foot after Tuesday's game and was seen wearing the boot in the clubhouse Wednesday.
St. Louis opens a three-game series at home Friday against the Chicago Cubs. RHP Shelby Miller (8-9, 4.26 ERA) is slated to start against Chicago LHP Felix Doubront (2-4, 6.07 ERA).
Pittsburgh is off Thursday before the Pirates continue their six-game homestand against the Cincinnati Reds. RHP Edinson Volquez (11-7, 3.56 ERA) starts the opener against his former team and RHP Mike Leake (10-11, 3.51 ERA).
Pittsburgh centerfielder Andrew McCutchen was in the lineup, a day after he was removed from a game because of discomfort in the same area of his ribs that caused him to go on the 15-day DL earlier this month. McCutchen finished 1 for 3 with a RBI. ''We're always going to be a better team with him in the lineup,'' Hurdle said.