Rowand hit a three-run homer after Cook left with a sore shoulder, Jonathan Sanchez tossed five solid innings and the Giants shaved Colorado's NL wild card lead to one game with a 6-3 victory over the Rockies on Friday night.
"Trying to score as many runs against this team is key because they're not ever going to quit," Rowand said. "You saw it in the ninth inning. They can score runs with the best of them and we have to score as many as we can as early as we can to give our pitcher a chance to settle down a little bit."
Sanchez (6-10) allowed an unearned run and two hits to win for just the third time since his no-hitter against San Diego on July 10. The left-hander's strong outing couldn't have come at a more opportune time for the Giants, who got off to a fast start in the four-game set between surprising playoff contenders.
Rowand's 11th homer off Josh Fogg gave San Francisco a 6-1 lead and the Giants bullpen escaped several jams, including one in the ninth.
While the music blared in the San Francisco clubhouse, Cook found a sliver of hope and humor despite an inflamed shoulder that knocked him out of the game in the fourth.
"I'm not too concerned. The last time I was on the DL, we went to the World Series," Cook cracked.
Cook was removed after walking the leadoff hitter on four ugly pitches.
"Hopefully it's just one of those things that came on real quick and we can get rid of it real quick," he said.
The Rockies played without star shortstop Troy Tulowitzki, who was ill, and then watched their ace head to the clubhouse after throwing just 47 pitches.
"That game didn't matter at that point," Rockies infielder Ian Stewart said. "We just hope that he's all right."
Cook will be re-examined Saturday, but at the minimum, he'll miss his next start, Rockies manager Jim Tracy said.
Sanchez struck out eight and walked four while handing the Rockies a rare setback at Coors Field, where Colorado had won 25 of its first 35 games under Tracy, who took over from fired manager Clint Hurdle on May 29.
Cook (10-6), who allowed four earned runs and three hits with four walks, said he didn't think the discomfort in his shoulder was related to any mechanical changes he might have made to account for a sprained big toe.
It was a disappointing series opener for Colorado and the large crowd at Coors Field. The Rockies had gone 50-25 since Tracy took over, becoming just the seventh team in major league history to go 15 games over .500 after being as many as a dozen under .500 in one season. But they got off to a slow start and finished with three errors.
"It was a tough one tonight," Tracy said. "There's no sugarcoating it. We did not play well tonight."
Cook gave up three runs in the first before the crowd of 43,666 had even settled in. Bengie Molina drove in a run with a ground-rule double, Nate Schierholtz followed with a sacrifice fly and Travis Ishikawa punched a run-scoring single up the middle.
The Rockies had numerous scoring opportunities squelched by San Francisco before loading the bases on two walks and a hit batter in the seventh. Left-hander Jeremy Affeldt came in and got Helton to hit into a 1-2-3 double play on a full-count 96 mph fastball to end the threat.
"When he hit it back to me, I was probably more overwhelmed with joy than anything else," Affeldt said.
Seth Smith connected for a pinch-hit homer off Affeldt in the eighth.
With Tulowitzki ailing, Clint Barmes moved over from second base to play shortstop, Stewart moved from third to second and Garrett Atkins played third base and was inserted into the cleanup spot despite his .226 average and eight home runs.
Winning the opener not only tightened the wild-card race but it prevented the Giants from falling three games off the pace heading into a three-day stretch during which they'll face double-digit winners Jorge de La Rosa, Ubaldo Jimenez and Jason Marquis.
"It's big for us," Giants manager Bruce Bochy said.
The Giants were without their star infielder, Freddy Sanchez, who sat out his fourth straight game with a sore left shoulder. ... Rockies hitters have struck out 78 times in the last seven games.