The Boston Red Sox go for the series sweep on Thursday when they close out a three-game set with the Seattle Mariners at Fenway Park.

Wednesday's game went 15 innings and lasted more than five hours, but Boston came away with a 5-4 victory on Stephen Drew's walk-off single with two outs. The win coincided with Tampa Bay's loss to Arizona, as the Red Sox (65-44) overtook the Rays and grabbed a half-game lead in the American League East.

Boston has made a habit of dramatic victories, as the team has won in walk-off fashion a major league-best 10 times this season.

"We somehow find some energy late in the game," manager John Farrell said. "It's been many different guys that have been the reason for the walk-off. I can tell you, the conversation each time we're at the plate in the extra innings, we're looking for something to draw energy from to make one last push. We were able to do that here again (on Wednesday)."

Both teams had chances to end it in extra innings, but ultimately it was Drew who delivered his second walk-off hit of the season. In the top of the 15th, Sox left fielder Jonny Gomes made a diving catch on a line drive and then ran in to tag second base himself to double off Raul Ibanez, who represented the go-ahead run but misjudged the play.

If the Red Sox hope to pull off the sweep, they'll have to do so against M's ace Felix Hernandez, whose 2.34 ERA tops the American League. The right-hander has not lost since May 25, going 7-0 with a 2.18 ERA in that span. In his last outing, Hernandez pitched a full nine frames against Minnesota but walked away with a no-decision in the 13-inning contest despite allowing only one run.

"It was vintage Felix," said bench coach Robby Thompson, who is filling in as acting manager while Eric Wedge recovers from a mild stroke. "But obviously we didn't have a lot of run support for him, and we squandered some opportunities. But Felix was Felix."

Boston's Ryan Dempster looks to atone for a July 11 start against Seattle, in which he was chased after giving up seven runs on nine hits in 3 1/3 innings. The right-hander was sharper his last time out, allowing two runs on six hits in 5 1/3 innings at Baltimore on Saturday.

The Red Sox have won five straight in the head-to-head series.