SAN FRANCISCO -- Matt Cain's right hamstring tightened on his 25th pitch of the game. Same thing happened again on the next one.
He summoned the trainer to the mound and was taken out by manager Bruce Bochy. By acting so promptly, he's hoping the injury won't be too serious.
The right-hander's strained hamstring was the primary concern after the San Francisco Giants had their 10-game winning streak against NL West teams halted in a 5-2 loss to the Colorado Rockies on Friday night.
Cain will undergo an MRI on Saturday.
"Hopefully, we caught it early enough where it won't be a big deal," Cain said. "It's discouraging, but you can't sit here and dwell on it. Just try to get this thing right and get back out there."
Cain went 1 2-3 innings before being replaced by Albert Suarez (1-1), who gave up three runs over five innings. Suarez also took a grounder off his left leg in the third but stayed in the game.
Two of the runs Suarez surrendered came in the inning where he was hit on the leg by a liner from Tony Wolters. The ball bounced off Suarez and into right field for a leadoff double.
Suarez picked up his first big-league RBI on a fielder's choice in the third.
"He did a nice job," Bochy said. "We just couldn't do anything offensively."
Tyler Chatwood (6-3) threw seven masterful innings and allowed just one unearned run as he continues to get stronger and stronger from a second Tommy John surgery in July 2014.
The command of Chatwood (6-3) was stellar in becoming the sixth Rockies pitcher to go seven or more innings, allow no earned runs and walk none at Coors Field. The last time the feat happened was by Juan Nicasio on July 15, 2011.
"They were coming out of the gates kind of swinging," Chatwood said. "I was able to execute some pitches and get some quick outs."
The Rockies were hoping for this kind of success this season from Chatwood, but really didn't expect it. Not this soon, given that he only made a few minor league appearances last season.
"That's what we talked to Chatty about in spring training, just to keep your expectations realistic, because he's such a competitor and a perfectionist," Rockies manager Walt Weiss said. "He's gone above and beyond so far this year."
Chatwood is even finding success at Coors Field after being so dominant on the road. His home ERA is 5.10, while his road mark is a scant 0.53, which is tops in the league among starters.
"Chatwood threw well and just couldn't mount much there," Bochy said. "That was the difference in the game. They pitched very well tonight."
Cain leaves early as Giants lose 5-2 to Rockies