CINCINNATI -- The Pittsburgh Pirates' NL Central chances were hurt when Todd Frazier had a tying two-run homer in the seventh inning and Ramon Santiago hit a grand slam in the 10th, powering the Cincinnati Reds to a 10-6 victory on Saturday.
Pittsburgh started the day a game behind first-place St. Louis, which played at Arizona later. The Pirates have already clinched at least a wild card and would host that game on Wednesday.
John Axford (0-1) walked Frazier to open the 10th and gave up Chris Heisey's single and another walk with one out. Left-hander Bobby LaFromboise relieved, retired Bryan Pena on a shallow fly out, then gave up Santiago's first career grand slam.
Dylan Axelrod (2-1) retired the side in the top of the 10th.
For second year in a row, the Pirates are finishing the regular season in Cincinnati on a playoff surge. Last year, they swept a three-game series at Great American Ball Park to clinch home-field advantage in the wild card game, and then beat the Reds at PNC Park in that one, too.
The Pirates' latest push includes 13 wins in the last 17 games. The loss on Saturday stalled their climb toward the top - they haven't been in first place since April 8 - and gave the Cardinals some room.
The Reds snapped a club-record streak of 45 consecutive losses when they allowed at least six runs in a game. Their bullpen got its first win since the All-Star break - Reds relievers are 1-17 over that span.
The Reds are 24-42 since the All-Star break. They'll at least tie the club record for fewest wins since the All-Star game. The 1933 team won 25 for the previous mark.
Pittsburgh had to overcome a rare off-day by Francisco Liriano, who gave up five runs in five innings. It was only the second time in 14 starts since the All-Star break that he'd allowed more than two runs. He remained 0-5 career in the regular season against the Reds, although he beat them in the wild card game last season.
Pirates: Catcher Russell Martin was out of the lineup with a sore left hamstring that began bothering him on Wednesday.
Reds: Center fielder Billy Hamilton was out of the lineup and won't play on Sunday, either, because of a concussion suffered on Wednesday. Hamilton leads all NL rookies in runs, hits, doubles, stolen bases and RBIs.
Pirates: Gerrit Cole (11-5) tries to extend his streak. The right-hander has won each of his last four starts.
Reds: Johnny Cueto (19-9) tries to become the Reds' first 20-game winner since left-hander Danny Jackson in 1988 and the first Reds right-hander since Sammy Ellis in 1965.