DENVER -- Rockies pitcher Aaron Cook left Friday night's 6-3 loss to the Giants with a sore right shoulder after facing one batter in the fourth inning.

That means he had five innings to fight back the pain and fear that comes with such a situation. He said Dr. Thomas J. Noonan, the team's medical director, told him it could be simple inflammation at the front of the soulder, but he won't have a thorough examination until the swelling subsides.

So with some positive words from the doc, Cook's sense of humor had time to return.

"I'm not too concerned," Cook said. "The last time I went on the DL, we went to the World Series."

But his suffering a torn oblique muscle back in 2007 and watching the team play so well that he actually was able to return for Game 4 against the Red Sox was one of those bad circumstances turned good. It's not exactly a part of the Rockies' 2009 game plan. The loss to the Giants pulled them to a game behind the Rockies in the National League Wild Card standings and kept the Rockies from tightening the gap with the first-place Dodgers.

Cook (10-6) had been battling a hyperextension of the right big toe quietly, until Aug. 6 when he aggravated it while backing up third base during a game against the Phillies. He left that one after five innings, saw a specialist and had his next start delayed.

After nine days off, Cook struggled Sunday against the Marlins, giving up eight hits and seven runs in 2 1/3 innings.

Friday's first inning looked similar. He gave up three runs on three first-inning hits. He settled, however, and threw unblemished second and third innings. But when he walked Nate Schierholtz to open the fourth, it was clear something was wrong.

"The four pitches that he threw to walk [Schierholtz], there was nothing that looked good about them," Rockies manager Jim Tracy said.

Josh Fogg replaced Cook, and Travis Ishikawa reached on a fielding error by second baseman Ian Stewart. Aaron Rowand followed with a three-run homer off Fogg for a 6-1 lead.

Tracy said it isn't clear Cook is going to the disabled list, but it's highly unlikely he will start Wednesday at home against the Dodgers. Tracy said he wanted Cook to be examined further before commenting. However, Adam Eaton and Fogg are candidates on the roster to step in, or the club could promote someone from the Minors.

Cook added that he does not believe the shoulder injury was related to the toe injury. The Rockies had feared that the toe injury could lead to a mechanical change, which could put him at risk for an injury to another area.

Cook said Noonan's initial opinion was "more positive than I was expecting," but he added that a lot depends on how the shoulder heals. That was one reason he could quip that his pain could be the Rockies' good-luck charm.

"I try to make light of it, but the fact is we're a good baseball team," Cook said. "We've got four other starters that have been pitching outstanding."