The Rays come into tonight's opener trailing the New York Yankees by 2 1/2 games in the American League East. The Red Sox, though, are 10 games back in the divisional race.
Boston did not help its cause any this weekend, as it was swept in a three- game set by the Chicago White Sox, losing both ends of a doubleheader on Saturday, then blowing a ninth-inning lead on Sunday before falling 7-5.
Jonathan Papelbon (5-6) took the loss and was saddled with his seventh blown save of the year, charged with four runs and two hits with a pair of walks over 1 1/3 innings.
"We worked hard and went to the ninth with a two-run lead," said Boston manager Terry Francona. "We felt pretty good about ourselves. But then we walk away an hour later with a loss and it doesn't feel good."
Heading to the hill for the Red Sox tonight will be left-hander Jon Lester, who has won four of his last five starts. Lester beat the Baltimore Orioles on Wednesday, but allowed five runs and eight hits in six innings. He is 15-8 on the year with a 3.27 ERA.
Lester beat the Rays two starts ago with a terrific effort and is 8-3 lifetime against them with a 3.86 ERA in 15 starts.
Tampa, meanwhile, failed to gain any ground on the Yankees on Sunday, as it dropped an 8-7 decision to the Baltimore Orioles in the finale of a three-game set.
Evan Longoria, B.J. Upton and Rocco Baldelli all hit two-run homers in defeat for the Rays, while Dan Wheeler (2-2) was charged with the loss after giving up two runs on two walks after getting just one out for Tampa Bay.
Getting the call for the Rays tonight will be righty Jeff Niemann, who has had two awful outings after a stint on the disabled list. After allowing 10 runs in 3 1/3 innings on August 25, Niemann was again charged with the loss last Tuesday against Toronto, which battered him for seven runs and seven hits in five innings.
Niemann, who is 10-5 on the year with a 3.97 ERA, is 2-1 in three starts against the Red Sox with a 3.94 ERA.