Brian Wilson's throwing session was cut short Wednesday, leaving the San Francisco Giants closer's ability to pitch on Opening Day in doubt, the San Jose Mercury News reported on its website.

"It didn't feel as good as we hoped, so we backed him off," Giants manager Bruce Bochy told the newspaper.

Just Tuesday, the Giants had been encouraged by Wilson's progress and were optimistic he would be ready for Opening Day.

Wilson, who hadn't pitched in six days since straining his left oblique, said he wasn't surprised to feel some discomfort after throwing at "a high level" but said he wouldn't fight Bochy if told to begin the season on the disabled list.

"I'm an employee. I'm not an investor," Wilson told the newspaper. "They do what's necessary and I follow orders. There might be disagreement, but whatever they feel is necessary has to be right. I'll agree with whatever they want to do.

"I don't own teams. I throw a baseball. If they say, come game time, that I'm not ready, then I don't have the right to argue. That would do no good," he said.

Wilson didn't call it a setback, though, and said he might try to play catch again Thursday if trainers give him the go-ahead.