MINNEAPOLIS -- One bad pitch. One bad inning. Nearly every outing, that has been the story for Jon Lester.

At some point, does it add up to one lost season?

Lester gave up five runs in the fifth inning tonight, three on an up-and-in fastball that Justin Morneau smoked over the right-field wall. It wrecked an otherwise good outing for Lester.

Once, that's an anomaly. Good hitters get their hits. But Lester has given up five or more runs six times this season, and most of those drubbings have come in one decisive inning. His ERA now stands at 6.05, his record at 3-5.

"I felt good. Made one pitch. One pitch cost me three runs. That's the ballgame right there," a somber Lester said in the clubhouse after the game.

Lester had turned in an excellent start last week against the Blue Jays, giving rise to the hope that he might be over his struggles. But this start seemed eerily like the appearance before that, where he seemed to be pitching well, but was suddenly unable to get key outs and gave up five runs to the Seattle Mariners.

"I think, for the most part, when you look back, it can come down to one pitch," manager Terry Francona said. It's almost the same thing as Seattle. It looked like he had a chance to get out of it, and all of a sudden, there's a crooked number on the board."

Lester said he can't figure out what's wrong. It's not a concentration issue, he said.

"I wouldn't say lapse -- obviously I'm trying to get outs and focus on that. I don't think it's a mental lapse or anything like that. I'm just not executing pitches," he said.

"I don't know what to tell you guys. I don't really have any answers for you."

Lester is striking out more than a batter per inning -- a career-high rate for him -- and his stuff looks sharp. But in every outing, he seems to run into a bad stretch, whether it be a game-changing home run or a series of weak ground balls, or even a fielding gaffe.

"That's what its come down to, a few times. I feel like he's so much closer to being real good and dominant, than he is to the five run inning," Francona said.

Lester said no amount of between-starts preparation can cure this. He is already working as hard as possible.

His next step is simply to make his next start in five days, and do it right this time.

"I go to Toronto and turn it around, hopefully, and keep on executing pitches," he said.