(Reuters) - The Boston Red Sox blunted Detroit ace Justin Verlander on the way to a 6-3 home victory on Tuesday to enjoy a positive winning record for the first time this season.

Daniel Nava hit a three-run double in the fourth inning to set up a 4-0 lead that was enough for Boston to improve to 25-24 on the season.

After losing 10 of their first 14 games, the Red Sox under new manager Bobby Valentine continued their slow climb back into contention in the American League East, where they now trail first-place by just 3 1/2 games.

"We're looking at it like we've got good momentum," Nava told reporters. "We've got things going in the right direction. There's a lot of season left."

Reigning Cy Young winner and the American League's Most Valuable Player, Verlander allowed five runs in six innings to lose his second consecutive start for the Tigers (23-26).

"Justin wasn't as sharp as normal," Detroit manager Jim Leyland said. "But give them credit. They swung the bats real good and we just couldn't get enough offense going."

Prince Fielder slugged a home run in the sixth and added an RBI in the seventh to pull Detroit within 5-3 but David Ortiz hit a solo blast in the bottom of the seventh to extend Boston's lead.

Ortiz went 3-for-4 with two doubles in the absence of team mate Dustin Pedroia, who suffered a thumb injury on Monday.

Daniel Bard tossed 5 1/3 innings to get the win for Boston, and Alfredo Aceves handled the ninth for his 12th save of the season.

Rain held up play for 38 minutes in the eighth inning before Boston resumed their march to victory.