The Athletics took the series opener on Monday, 6-1, getting to Daisuke Matsuzaka for five runs in the first two innings before the Sox's bullpen took over and Clayton Mortensen and Mark Melancon combined to throw seven innings of one-run ball. The Red Sox can't afford another short outing from their starter and need Lester to start pitching like the team's ace.
Lester is 5-5 with a 4.53 ERA in what's been an up-and-down season for him and the Sox. Following a 7-2 homestand, Boston is 2-3 to start a seven-game West Coast road trip.
Lester won his last start on Wednesday vs. the Blue Jays, allowing four runs in seven innings. That came after he allowed just three runs in seven innings on June 22 vs. the Braves, yet took the loss. Lester didn't think he pitched particularly well his last time out, but the southpaw was happy to get the victory even though he hasn't discovered the root of his inconsistency.
"A win always takes away the questioning in the back of your mind," Lester said. "A win is a win. I'm not going to overanalyze anything."
Still, Oakland manager Bob Melvin views Boston as a dangerous team. The A's won two out of three games at Fenway Park at the start of May, but the Sox are 31-25 since then and have climbed out of the American League East cellar.
"It's a different team than we saw when we were in Boston, a team that's scoring a lot of runs and playing well at this point," Melvin said. "Different roster composition, but playing Red Sox baseball and playing well."
Oakland was a .500 ballclub when it visited Boston but is three games under the break-even mark since. The A's have won 13 of their last 20 games, though.
Similar to Lester, Bartolo Colon has been inconsistent in 2012. The right-hander will be activated from the 15-day disabled list and start on Tuesday. He's been sidelined with a strained oblique but will return from the DL sooner than expected.
Colon knows the Red Sox well and will make his 25th career start against them. He's 8-11 with a 4.08 ERA in 25 career appearances against Boston. Colon was 6-7 with a 4.22 ERA in 15 starts prior to his injury.
Red Sox: Middlebrooks nursing hamstring
Will Middlebrooks was not in the Sox's lineup on Monday, one day after leaving Sunday's game vs. the Mariners with left hamstring tightness. There's a chance the rookie won't play in the series against Oakland.
Middlebrooks left Sunday's game in the bottom of the ninth inning. The third baseman also battled a hamstring issue about six weeks ago, but he recovered quickly.
"The latest on Will is that he feels better [Monday] than he did yesterday and better than he expected to be [Monday]," said Red Sox manager Bobby Valentine. "That's the only news we have -- that's good. It's not discolored, and that's good, but it's going to be some days [before he can play]."
Nick Punto started at third on Monday. The Red Sox have 13 pitchers and 12 position players, leaving Valentine with only catcher Kelly Shoppach and utility man Brent Lillibridge off the bench with Middlebrooks out.
The Sox will likely add a position player to the active roster on Tuesday, but its unclear whether Middlebrooks will head to the disabled list or if Boston will send down a pitcher.
Athletics: Suzuki expected to start
Kurt Suzuki will be back behind the plate on Tuesday after getting a day off on Monday.
Derek Norris started for Suzuki on Monday, going 1-for-3 with two runs and his first career stolen base.
Suzuki, who also sat on Sunday vs. the Rangers, is hitting .208 with 16 RBIs in 65 games this season.
Chris Carter was also out of the lineup on Monday, though he's expected to start on Tuesday.
Melvin said he's inclined to play the first baseman against left-handed starters, so Tuesday offers a chance for Carter to start. Oakland recalled him from Triple-A Sacramento on Friday and he homered in each of his first two games.
Carter is 3-for-7 with two homers, two RBIs and four runs, but he has not played since Saturday vs. the Rangers.
Red Sox slugger David Ortiz hasn't had much success against Colon in his career, going 6-for-45 with one homer and 15 strikeouts.
The Athletics have homered in 13 straight games, the club's longest streak since 2004, when they homered in 14 consecutive games from April 27-May 12.