Jurrjens said the soreness originated near his rib cage, but was not related to his oblique muscle. He believed it was a cramp and that he could have continued pitching, but he left the game for precautionary reasons.
"I was just trying to be careful," said Jurrjens, who was 1-2 with a 3.60 ERA in five outings prior to Thursday's game. "It's too close to the season to risk anything."
Jurrjens initially felt the pain while pitching to the Blue Jays' No. 2 hitter, Yunel Escobar. Jurrjens remained in the game to strike out slugger Jose Bautista, but did not come out of the dugout to start the second inning.
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The 25-year-old said his ability to bounce back in the at-bat against Bautista proved the injury was only minor.
"If it was really bad, I don't think I would be able to pitch to Bautista," Jurrjens said. "It makes me feel a litle better about it. We just want to be smart. I really wanted to go out there, but they didn't want me to ... make it worse."
Jurrjens volunteered the information to the Braves' coaching staff, because he did not want the problem to become a lingering issue. Last year, he spent 61 days on the disabled list with a left hamstring issue.
"I'm not trying to hide any injury issues," Jurrjens said. "It didn't really help me last year when I tried to hide it. [I'm] just trying to be 100 percent when I take the mound and try to help this team out."
The native of Curacao is expected to make his next scheduled start on Tuesday against the Twins at Turner Field. Last season, Jurrjens went 7-6 with a 4.64 ERA in 20 starts with Atlanta.