Pittsburgh Pirates starting pitcher Mitch Keller delivers during the first inning against the St. Louis Cardinals on Monday, July 22, in Pittsburgh. Associated Press

PITTSBURGH — Nick Gonzales hit a go-ahead RBI single in the eighth inning after Mitch Keller allowed one run in the first seven, and the Pittsburgh Pirates won for the seventh time in eight games, 2-1 over the St. Louis Cardinals in a matchup of NL wild-card contenders Monday night.

Bryan Reynolds led off the eighth with a single to left before advancing to second on a wild pitch. With one out, Gonzales sneaked a slow dribbler off John King (3-2) through the right side of the infield.

Gonzales hit a late-inning, go-ahead single for the second time in four games. He did it in the ninth inning against Philadelphia on Friday, giving the Pirates an 8-7 win.

Keller gave up six hits in seven innings, striking out three and walking two, before Aroldis Chapman (2-4) pitched a perfect eighth. David Bednar allowed a two-out single to Paul Goldschmidt in the ninth before striking out Nolan Gorman for his 18th save.

Andrew McCutchen doubled to left in the third inning and Oneil Cruz put Pittsburgh ahead on a two-out RBI single to left.

Gorman tied it 1-all with a leadoff home run, his 19th, driven 362 feet off the right-field foul pole. Brendan Donovan then hit a sharp grounder off Keller’s curveball with runners on first and second, but first baseman Rowdy Tellez made a diving stop to keep it from slipping down the line.

The Pirates left a runner in scoring position in each of the first four innings.

Cruz stole second in the first and third innings ahead of groundouts from Gonzales. Tellez led off the second with a double but only reached third. Jack Suwinski stole second with two outs in the fourth, but Andre Pallante struck out Connor Joe.

Pallante went six innings for St. Louis, allowing one run on three hits with three strikeouts and two walks.

Pirates rookie RHP Paul Skenes (6-0, 1.90 ERA) will pitch Tuesday for the first time since starting the All-Star Game for the National League, going opposite Cardinals RHP Lance Lynn (5-4, 4.39).