Tampa Bay (35-22) at Boston (35-25)

The Boston Red Sox probably didn’t think they would be battling the Tampa Bay Rays for first place in the AL East this season.

The Rays will be trying to build on their division lead on Tuesday when they open a three-game series at Fenway Park with the Red Sox, who will be missing slugger David Ortiz.

Tampa Bay (35-22), which has never had a winning season, owns the best record in the AL and a 1 1/2-game lead over the second-place Red Sox (35-25) in the East. The Rays just won the last three games of their four-game set with the AL Central-leading Chicago White Sox to move 13 games over .500 for the first time in the team’s 11-season history.

Gabe Gross hit a walk-off homer in the 10th inning of Sunday’s 4-3 win in the series finale, two days after Cliff Floyd hit a walk-off shot. Tampa Bay has won eight of 10.

“We’re getting to the point now where we’re not satisfied with yesterday’s win,” manager Joe Maddon said. “It’s a whole team effort right now. … I think every night we go out there is a good barometer. There are no breaks (in the schedule).”

A trip to Fenway might be an especially good barometer for the Rays, however. Tampa Bay was swept in three games in their last trip to Boston from May 2-4 and are just 23-64 all-time at Fenway.

The Red Sox won the first three games of their series against Baltimore before blowing an eighth-inning lead to lose 6-3 in Monday’s finale. Even worse, Boston learned that Ortiz, who leads the Red Sox with 13 homers and 43 RBIs, will be placed on the 15-day disabled list with a partially torn tendon in his left wrist.

“He’s a big part of the team,” said Manny Ramirez, who homered in his third straight game. “We have to keep battling without David. Let’s wait for him and pray that he’ll get better soon.”

Ramirez, who now has 502 homers, was the designated hitter in place of Ortiz, and will likely continue in that role instead of playing left field.

“The team is playing great, we take three out of four, and we’re going home,” said Ramirez, batting .382 (13-for-34) with 11 RBIs in his last eight games.

Justin Masterson (1-0, 1.46 ERA) will be called up from Triple-A Pawtucket to take Ortiz’s roster spot and make his third start in Tuesday’s opener. He gave up one run in 6 1-3 innings of a 2-1 win over Kansas City on May 20, but was sent down after the game to make room for Bartolo Colon.

Masterson made his major league debut on April 24, allowing one run in six innings without getting a decision in Boston’s 7-5 loss to the Los Angeles Angels. This time, he is filling in for the injured Daisuke Matsuzaka, who is out for at least two starts.

“It’s nice to know that when we have to fill a start, we get it by getting a kid we’re excited to watch pitch,” manager Terry Francona told Boston’s official team Web site.

Tampa Bay counters with Matt Garza (4-1, 3.78), who turned in the longest outing of his career on Wednesday, giving up two runs and striking out 10 in eight innings of a 5-3 win over Texas. He has won three straight decisions and his last two starts.

“I felt great, no doubt about it,” Garza told the Rays’ official Web site. “Numbers-wise, it was my best outing. I don’t want to let those guys down out there.”

Garza, acquired in an offseason trade with Minnesota, is 2-0 with a 3.45 ERA in three career starts against the Red Sox. He allowed three runs in five innings of the Rays’ 11-inning, 5-4 win over Boston on April 25.