By Bruce Levine–

CHICAGO (CBS) — The exasperation was spread around early for the Chicago Cubs on Thursday at Wrigley Field. It started with a lousy day for left-hander Jon Lester and morphed into a lack of concentration and decision-making by the team on the field.

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Despite all that was bad, the defending World Series champion Cubs didn’t fold up the tent. They fought back in memorable fashion. The effort was there. The result? Not so much, with the Cubs falling 13-10 to the Reds. But that wasn’t their biggest loss of the day.

Lester exited the game with left lat tightness and a nine-run deficit in the second inning. The Cubs sent Lester to see team orthopedic specialist Stephen Gryzlo at his Northwestern Memorial Hospital office. The team wasn’t sure what tests would be taken Thursday evening.

“He went to see the doc,” manager Joe Maddon said after the game and a brief meeting with Cubs president of baseball operations Theo Epstein. “I haven’t heard anything specific yet. The tight lat is what I also heard.”

Lester had a six-pitch first inning, but everything unraveled in the second. The Reds tagged him for nine runs, seven earned, and the Cubs fell behind 9-0 before he left the game with a team trainer.

Maddon and the staff could see that something was out of whack in the second inning for Lester.

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“You could see the velocity was down on everything a little bit,” Maddon said. “They were getting a lot of soft hits over the infielders’ heads. He was getting in on them but he wasn’t able to finish his pitches. They were able to fight him off. He was missing that last thing that helps you prevent those hitters from doing that basically or getting weaker contact.

“Obviously, something wasn’t right. The cutters were 84 to 85. I asked what was that pitch. I was told cutter. I said that is not quite right. It might have been bothering him from the beginning. He didn’t say anything, though. I went out to the mound he said his side was tight. You just make the move right there.”

Meanwhile, the Cubs did everything they could to fight back with a five-run inning in the fourth. They knocked out former Cubs starter Scott Feldman with a four-homer barrage, tying a franchise record for homers in a single inning. That included back-to-back-to-back homers from Alex Avila, Ian Happ and Javier Baez. Three more runs in the fifth had the game knotted up. The Cubs would hit six homers in total.

Long reliever Mike Mongomery did his usual splendid job in coming in on emergency relief in the second inning. Mongomery put up zeros in the next four innings he pitched, allowing the offense to fight back. Justin Grimm gave up a two-run homer in the seventh, allowing the game to toward Cincinnati with an 11-9 lead. The Cubs bullpen couldn’t shut down the Reds offense after Montgomery did his job.

Having started eight games this season, Montgomery would be the likely candidate to step in for Lester if the latter goes on the disabled list.

“I have been a starter for a good part of the year,” Montgomery said. “I am used to being stretched out like that. I just put in the work in between and get back to it.”

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Bruce Levine covers the Cubs and White Sox for 670 The Score and Follow him on Twitter @MLBBruceLevine.