Beckett will make his third start against Tampa Bay this season. The right-hander has allowed just three earned runs in 15 innings vs. the Rays. Since 2007, Beckett has a 2.46 ERA against Tampa Bay, the best mark among Major League qualifiers.
The Rays knotted the series with a 5-3 victory on Saturday night after falling to Boston on Friday, 3-1. But Tampa Bay will have to beat Beckett for the first time since 2009 to win the series.
Beckett wasn't sharp in his last outing, giving up five runs in the first inning against the Yankees on July 6. Still, he rebounded and held New York scoreless over his final three innings.
"It was tough, just rhythm-wise," said Beckett. "I was battling myself, especially in the first inning. I kind of sped up my mechanics there in the middle innings, and at least out of the windup, it made a difference. The stretch was [still] pretty tough."
Tampa Bay hands the ball to James Shields looking to open its 10-game homestand with a series win.
Shields didn't have a great first half of the season. He's 8-5 on the year with a 4.17 ERA and leads the Majors with 135 hits against him.
In his last three outings, the right-hander has given up 34 hits in 21 2/3 innings. Still, the Rays went 2-1 in those games.
"I feel really good in my delivery over the last three starts," Shields said. "Obviously, that shows I haven't walked that many guys, but the hits need to go down and we need to win some ballgames."
The Red Sox slipped back to .500 with Saturday's loss. Boston has not been below the break-even mark since it was 32-33 after a loss on June 16 vs. the Twins.
Red Sox: Gonzalez 'doubtful' for Sunday
First baseman Adrian Gonzalez was out of the lineup for the second time in as many nights on Saturday, the result of lower back spasms, and is considered "real doubtful" for Sunday's series finale.
Gonzalez was a late scratch from Friday's lineup after his back locked up on him when he bent down to greet a child in a stroller at a mall.
Valentine said he projects Gonzalez to return to the lineup by the start of next week, and the first baseman said it would take no more than three days.
"I felt better today," Gonzalez said. "There's still tightness there. If I need to, I can go out there. But they don't want me to push it and aggravate it."
Gonzalez had not missed a game this season prior to Friday.
Brent Lillibridge filled in for Gonzalez at first base on Saturday. David Ortiz could start at first on Sunday.
Jacoby Ellsury is 3-for-9 since being activated from the 60-day disabled list prior to Friday's game. The center fielder missed three months after dislocating his right shoulder on April 13 vs. the Rays at Fenway Park.
Ellsbury doubled in the eighth inning on Saturday and singled in the fifth.
Rays: Jennings slides out of leadoff spot
Desmond Jennings was not in the leadoff spot on Saturday for the second consecutive game in an attempt to get the outfielder out of a prolonged slump.
Jennings has hit in the leadoff spot in 52 of his 59 starts this season. He is batting .161 in his last 20 games in the leadoff spot.
"My biggest thing with Desmond, I want him to understand I wanted to move him down just to take some pressure off him," Rays manager Joe Maddon said. "And also permit him to work on certain things that are going to get him back to being the premier leadoff hitter that he is.
On Saturday, Jennings hit eighth and he went 1-for-2 with a single and a run.
"It's just a different mindset when you're hitting toward the bottom of the order," Maddon said. "Again, I'm hoping he relaxes a little bit, does not apply so much pressure to himself to be the table-setter, and sees the ball better, maybe redefine the strike zone."
The Red Sox are 12-17 in day games this year, while the Rays are 16-15.
Rays designated hitter Luke Scott is 11-for-27 (.407) in his career against Beckett with three home runs and eight RBIs.