The Pirates blew a four-run lead for the second straight night, but managed to come back behind McCutchen, who has more homers against Cincinnati than anyone else since 2009.
He tied it 5 in the ninth off Jonathan Broxton, filling in the closer's role because Aroldis Chapman had pitched four days in a row. He hit his 17th homer with two outs in the 11th off J.J. Hoover (1-7) for his ninth career multihomer game.
The Reds won the series opener 6-5 by rallying in the eighth inning against All-Star reliever Tony Watson, overcoming a four-run deficit. They pulled out of a four-run deficit again on Saturday but couldn't finish it off.
McCutchen has 20 career homers against Cincinnati, the most by any player in the majors since 2009. He's hit six of them this season, including three during the first two games of the series.
The Reds slipped to 7-3 on their 11-game homestand, remaining 1 1/2 games behind NL Central co-leaders Milwaukee and St. Louis. Cincinnati is 8-4 against the Pirates this season.
Pittsburgh is 2-4 on a trip to St. Louis and Cincinnati. The Pirates gave up two game-ending homers in St. Louis and blew a four-run lead in the series opener, a 6-5 Reds win.
The Reds got in position to win it with a pair of homers.
Chris Heisey batted for Mike Leake in the sixth and hit a two-run shot off Charlie Morton. Todd Frazier -- who will participate in the All-Star home run derby next week -- completed the comeback with a three-run shot off Morton, who had given up a total of six homers coming into the game.
All-Star Johnny Cueto (9-6) starts the final game of the series for Cincinnati. The Pirates plan to activate left-hander Francisco Liriano (1-6) off the disabled list. He has recovered from a strained oblique. ... McCutchen has hit safely in 11 of the 12 games against Cincinnati this season, going 19-for-46 with four doubles, five homers and seven RBIs. ... The Reds optioned reliever Curtis Partch, who got the win on Friday night, to Triple-A Louisville and brought up INF Neftali Soto, giving them four position players available on the bench. ... It was Heisey's eighth career pinch-hit homer, his second this season.
Copyright by STATS LLC and The Associated Press
CINCINNATI, OH - JULY 12: Mike Leake #44 of the Cincinnati Reds pitches in the first inning of the game against...