(Sports Network) - In a season that's been filled with monumental moments for the Tampa Bay Rays, the long-suffering franchise may have posted the biggest win in team history last night.

The American League East leaders hope to build off the momentum of Tuesday's comeback victory over the Boston Red Sox when the two divisional foes wrap up an important three-game set this evening at Fenway Park.

Boston cut the Rays' advantage atop the East to a mere half-game with a 3-0 triumph in Monday's series opener, then put itself in position to reclaim first place by taking a one-run lead into the ninth inning of last night's tilt. However, Tampa Bay rallied for two runs off Sox All-Star closer Jonathan Papelbon in its final at-bat to pull out a thrilling 5-4 win.

Pinch-hitter Dan Johnson tied the contest at 4-4 when he greeted Papelbon (5-4) with a solo home run. Two batters later, Fernando Perez doubled off the Green Monster in left and scored the go-ahead run on Dioner Navarro's opposite-field double.

The Red Sox got the potential tying run to third base in the bottom of the ninth, but Rays reliever Troy Percival got Coco Crisp on a game-ending pop out to record his 28th save of the year.

Boston had taken a 4-3 lead on Jason Bay's two-run homer in the bottom of the eighth off Dan Wheeler (4-5), who wound up getting the victory despite blowing a save chance.

Mike Lowell also homered and finished 2-for-4 for the Red Sox, who lost for only the second time in their last eight games.

Tampa Bay, which had lost six of its last seven coming in, got six solid innings out of starter Scott Kazmir on the night. The hard-throwing lefty held Boston to two runs on five hits and left with a 3-2 lead.

The Red Sox will attempt to rebound tonight behind Josh Beckett, who eased a lot of worries among the organization with his performance at Texas last Friday.

Beckett, making his first start since August 17 due to inflammation in his throwing elbow, fired five shutout innings in his return to the mound to lead Boston to an 8-1 win over the Rangers. The ace right-hander yielded just four hits and struck out seven.

The hard-throwing Texan is 2-1 with a 2.57 earned run average over three starts against Tampa Bay this season, and 5-3 with a 3.59 ERA in eight lifetime encounters with the Rays.

The Rays will send out the struggling Andy Sonnanstine in this evening's finale. The second-year major leaguer is winless over his last three starts and allowed four runs or more in each of those outings, having compiled an 0-1 record and a subpar 7.47 ERA during that stretch.

Sonnanstine was last in action Friday in Toronto and received a loss after permitting four runs over six innings. The right-hander also gave up a home run on the evening, one of five long balls he has served up over his three most recent mound trips.

The 25-year-old has faced the Red Sox four times previously, with all of those starts coming during his rookie season of 2007. He is 1-1 with an 8.85 ERA all-time against Boston.

Last night's victory by the Rays was the first by the visitor in this year's season series between the teams. Boston is 7-1 against Tampa Bay at Fenway Park in 2008 but has lost all six of its tests at Tropicana Field.

The Rays halted a nine-game losing streak in Boston on Tuesday, but the club is a woeful 6-30 in Beantown since 2005.