BOSTON — Will Middlebrooks’ reaction running down the first-base line Wednesday night might have summed up how his teammates were feeling when the Boston Red Sox finally got back to .500.

The slumping Middlebrooks pumped his fist a few times after hitting an RBI single with the bases loaded, capping a two-run rally in the eighth inning that sent the Red Sox over the Cincinnati Reds 4-3 for a sweep of the two-game interleague series.

“I just wanted to help the team win and to contribute,” Middlebrooks said.

Mired in a 2-for-19 stretch and coming off an 0-for-5 night with a pair of strikeouts, Middlebrooks sent a hard grounder up the middle for the go-ahead run.

“I’ve been frustrated but regardless if you’re 10 for 10 or

0 for 10 or whatever, you’re happy to contribute to a win in any way possible,” he said.

David Ortiz and Mike Napoli also drove in runs for Boston, which reached .500 for the first time since the fourth game of the season.

The Red Sox failed in eight previous chances.

“I don’t think it was a mental hurdle,” Manager John Farrell said. “I never heard too many of us mention that we’re bumping up against .500 and taking a step back. It was just more of a situation inside games where we had opportunities that we haven’t cashed in on, finally we do tonight.”

Skip Schumaker hit a two-run homer for Cincinnati, which lost the opener to Boston 4-3 in 12 innings. It was the Reds’ 11th one-run loss, most in the majors.

“We play a lot of low-scoring, one-run games,” Manager Bryan Price said. “We’re battling and we’ll be whole soon, but until then we’ve got to find a way to create some distance between ourselves and our opponent. It will come down to making every single play over the course of those last three innings to win the game, and it can’t be like that every single day of a baseball season.”

Trailing 3-2 in the eighth, the Red Sox scored against two relievers.

“It’s tough,” Reds left fielder Chris Heisey said. “We felt like we had the game and let it slip away.”

Napoli drew a one-out walk from Manny Parra, J.J. Hoover (1-4) walked pinch-hitter Jonny Gomes and A.J. Pierzynski’s ground-rule double made it 3-3. Jackie Bradley Jr. was intentionally walked before Middlebrooks had his tiebreaking hit.

Craig Breslow (2-0), who also got the win in Tuesday’s game, pitched one hitless inning. Koji Uehara struck out the final three batters for his eighth save.

Cincinnati starter Mike Leake pitched seven strong innings and was in line for the win before Boston rallied. He gave up two runs on eight hits, walking two and striking out four.

Jake Peavy of Boston allowed three or fewer runs for the sixth time in seven starts, giving up three runs on four hits with four walks and five strikeouts.

The Reds grabbed a 3-2 lead in the seventh when Roger Bernadina bounced a slow groundout to second against relief pitcher Chris Capuano with the bases loaded.

In the bottom half, Heisey made a nice inning-ending running catch on Shane Victorino’s liner into the gap with the tying run on second.

Boston tied it with a pair of runs in the sixth on a run-scoring single by Ortiz and RBI double by Napoli.