"I'm going to pitch Sunday -- 100 percent," he said.
Meche said he passed an MRI exam on Wednesday, a great relief for him.
"Everything's all right," he said. "That's really good news. I told you guys the other night that I really didn't think anything was wrong and that I was able to pitch and at times it'd come back and go away."
Even after making those assurances to reporters after leaving Tuesday night's game against Toronto in the fourth inning, he confessed to being worried about the MRI.
"I wasn't able to sleep terribly well the night before because I kept second-guessing myself and thinking, 'Man, what if it is something?' " Meche said.
"I kept telling myself that [it was nothing], but what if it is?"
His wife Stacy reassured him and told him all would be well and she was right.
Meche planned to do some light cardio and bike riding but no throwing for a couple days to help the stiffness dissipate.
"I know my velocity is there, I can't use it because of my back," Meche said. "I want to pitch at more of a higher level effort, because that's what I've always done. So if some day I go out there and it feels good, I'm going to let it rip."
Meche, 1-2 with a 3.77 ERA in five starts, is encouraged because he's been getting a lot of ground-ball outs and hasn't been touched for a home run in 31 innings.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.