Burnett left Friday's game against the Marlins in the fifth inning with what the team called "groin soreness." He will be evaluated Saturday. The right-hander said his right groin affected him intermittently throughout the game, in which he allowed two runs on five hits and six walks while striking out four in 4 1/3 innings.
"It was in and out," Burnett said. "It was pretty uncomfortable the last inning, but it came on early and went away. That's why I didn't feel like it was too serious.
"Pretty much every pitch out of the stretch, more so out of the windup, the last inning I felt it a lot. That ain't me. I don't walk guys like that. I'm going to walk my guys here and there, but I couldn't throw the ball anywhere I wanted to. Hopefully we'll find out tomorrow that it's not that bad."
Burnett, 37, also walked six batters in 5 2/3 innings in his previous start Sunday at Wrigley Field, but he said he did not have any problems before Friday's start.
"I'd just say it felt more snug that anything," he said. "Like everything was tight, opposed to something going. I guess that's a positive. I tried to mask it, but I guess I didn't, huh? ... I'm not too concerned about it, but then again, you never know. I'm not a spring chicken anymore. But it takes a lot to get me out of the ballgame. I'm not happy about that."