Barry Bonds found his elusive power stroke in Denver's thin air.
After circling the bases, Bonds knocked fists with teammates Moises Alou and Pedro Feliz and manager Felipe Alou as he descended into the third-base dugout to jeers and a scattering of applause.
Bonds moved within five home runs of Babe Ruth for the most by a left-handed hitter with 714. It came in his 31st at-bat and 13th game.
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San Francisco's surly slugger had never gone deeper into a season without circling the bases when healthy. In 1998, he also didn't homer until his 13th game, the longest season-opening drought of his career.
Hounded by steroid suspicions, a federal probe into his testimony in the BALCO steroid case and baseball's investigation of performance-enhancing drugs, Bonds got off to a slow start this season despite a stellar spring.
Plagued also by sore knees, a swollen left elbow and few pitchers willing to challenge him — he walked 19 times before hitting his first home run — Bonds brought a .200 batting average and just one RBI into Saturday night's game.
In the series opener Friday night, he swung at two of the 17 pitches he saw, flying out to the warning track in center field his first time up, then drawing three straight walks before grounding out to first.
Rockies manager Clint Hurdle vowed not to pitch to Bonds if he didn't have to: "Let him find his rhythm somewhere else."
Bonds found it Saturday night in Denver, making Cook his 417th victim and giving the Giants a 2-0 lead.
On Friday night, Bonds, who has never been a fan of Denver despite his 25 home runs at Coors Field, the most by an opposing player, got the usual treatment as fans shouted "Juice!" every time he came up or made a play. One fan behind the Giants dugout wore a tall hat shaped like a syringe.
The crowd had barely settled in Saturday night when Bonds walked up to the plate, took a high fastball and then unleashed his first homer of 2006, trotting around the bases for a change and not just to first.