Hunter Pence hit one of San Francisco's three solo homers and reliever Yusmeiro Petit threw three sharp innings after starter Matt Cain left with a strained right hamstring as the Giants beat the Colorado Rockies 5-1 on Wednesday night.San Francisco Giants' Hunter Pence reacts after being called out on strikes against the Colorado Rockies in the first inning of a baseball game in Denver on Wednesday, May 21, 2014.San Francisco Giants starting pitcher Matt Cain, back, delivers a pitch while framed by Colorado Rockies batter Troy Tulowitzki, front left, and home plate umpire Adam Hamari in the first inning of a baseball game in Denver on Wednesday, May 21, 2014.Colorado Rockies starting pitcher Jhoulys Chacin works against the San Francisco Giants in the first inning of a baseball game in Denver on Wednesday, May 21, 2014.San Francisco Giants shortstop Brandon Crawford fields ground ball off the bat of Colorado Rockies' Troy Tulowitzki in the first inning of a baseball game in Denver on Wednesday, May 21, 2014.