DENVER -- Mike Yastrzemski hit a three-run homer, one of four long balls by San Francisco, to help the NL West-leading Giants beat the Colorado Rockies 7-2 Friday night and become the season's first 100-win team.

154 games is the fastest the Giants have reached 100 wins in the live-ball era (since 1920). It's the first time they've been the first team in MLB with 100 wins since moving to San Francisco in 1958.

San Francisco leads the Los Angeles Dodgers by a game. The Giants have won 16 of 20.

Kervin Castro (1-0) tossed two innings for his first major league victory, and the Giants reached 100 wins for the first time since going 100-62 in 2003.

"It's a big accomplishment, but we're looking for more," San Francisco pitcher Alex Wood said.

The Giants haven't won the NL West since 2012, when they captured the second of three World Series titles in a five-year span. Coming into the season, they were lightly regarded with the Dodgers and San Diego Padres getting most of the attention, but they've surprised many.

"It's a big deal,'' manager Gabe Kapler said of winning 100 games. "We know our division is extraordinarily talented, but we also know that we're talented. Our goal was to win the division and not just sneak into the playoffs.''

San Francisco blew it open in the seventh. Yastrzemski followed singles by Brandon Crawford and Evan Longoria with his 25th homer off reliever Ashton Goudeau (1-1). The Giants tacked on another run on Buster Posey's RBI single.

Tommy La Stella, Crawford and Brandon Belt had solo home runs to give San Francisco a 3-2 lead after six. La Stella and Crawford had three hits each and Belt finished with two.

San Francisco has 234 home runs, one fewer than the club record set in 2001 when Barry Bonds hit 73. The Giants lead the NL in homers and are second in the majors to Toronto's 241 despite not having a player hit more than 27 this season.

Three players -- Belt, Crawford and Yastrzemski -- have 22 or more, and seven other players have reached double digits in home runs.

"So many of the home runs have been meaningful,'' Kapler said. "I can't help but think of the ones that changed a game for us. We're getting contributions from everyone on our roster.''

The Associated Press and ESPN's Stats & Information contributed to this story.