DENVER -- Trevor Brown made the San Francisco roster with his defense. He's proving he can give the Giants some timely offense, too.
Hunter Pence also hit a two-run home run to help San Francisco win for the fourth time in the last five games.
It was Brown's first multihomer game of his career, and his four RBI were also a career high. His only other home run this season broke up a no-hit bid in the eighth inning against Chris Hatcher of the Los Angeles Dodgers on Friday.
"We all know what we have in Buster, but to have another guy doing what he's doing, we're really excited for him," Samardzija said.
Brown is the first Giants player to hit a home run for his first three hits of the season since Kevin Mitchell did it in 1991.
"I was thinking the entire season I might end with three," Brown said. "Knock on wood, I still might. I didn't think my first three hits were going to be home runs. It's been a crazy first couple of games for me."
Just as impressive was his work behind the plate. He steered Samardzija through some tough middle innings to help him go deep into the game.
He also came up big defensively when he tagged out Carlos Gonzalez trying to score from first in the fifth inning.
"Normally I try to focus on the catching because it's my main job," Brown said. "It's fun to go out and have a good game on both sides."
Samardzija (1-0), who signed a $90 million, five-year contract in the offseason, tamed hitter-friendly Coors Field by scattering eight hits and striking out five. He allowed RBI singles to Mark Reynolds in the third and Nolan Arenado in the fifth.
He retired the next nine batters before leaving after throwing 111 pitches. Samardzija also got his first hit, a double, after Brown's first home run.
"I was thinking six, seven innings but I couldn't take him out," Giants manager Bruce Bochy said. "He just got better as he went."
Samardzija was locked in a pitcher's duel with Chatwood until Pence broke a 1-all tie with his two-run homer in the fifth, his second of the season.
The Rockies got one back in the bottom of the inning when Brandon Crawford and Angel Pagan let Arenado's blooper fall between them in the outfield, but Pagan threw out Gonzalez at home to keep the Giants ahead 3-2.
Pagan kept the sixth alive when he beat out a throw to first to avoid an inning-ending double play, and Brown followed with his first home run.
"I made two pitches that hurt me," Chatwood said. "The pitch that Pence hit out was what we wanted to do. It got to the spot and he beat me to the spot. The other two-run homer with two outs, I left the ball up and he hit out of the park."
Pagan reached again in the eighth off Gurka and stole second before Brown drilled another fastball into the left-field seats.
WEEK TO REMEMBER
Rockies rookie shortstop Trevor Story capped a historic start by winning NL Player of the Week honors. Story earned the award when he became the first major league player to hit seven home runs in the first six games of his career. He entered Monday leading the majors in homers and RBI (12), but he is trying to keep his torrid start in perspective.
"If I told you I expected to hit seven home runs, I would be lying to you," he said. "I really can't say that I thought it would be like this."
Samardzija helped keep Story grounded by fanning the rookie three times on breaking pitches. Story finished 0 for 4 and went without an RBI or a hit for the first time this season.
"Story, he's had a great start, but I'm worried about CarGo, (Gerardo) Parra, those big power lefties," Samardzija said. "We respect him as a player and we're going to keep pitching to him tough because he's proven what he can do."
Parra has a strong outfield arm and he showed it off in the third when Denard Span scored from second on a single by Pence. Parra went home with his throw, allowing Pence to advance to second. Brandon Belt followed with a single and this time Parra's throw cut down Pence at the plate.
Giants: C Posey was given the night off because of bruise on his right instep. Posey was hurt on a foul tip by the Dodgers' Chase Utley on Sunday. Posey was available to pinch hit and is expected to be back in the lineup on Wednesday. "We'll re-evaluate him tomorrow and if he needs another day then he's going to take it," Bochy said.
Rockies: RHP Jon Gray threw 64 pitches in a rehab start for Double-A Modesto on Sunday. Gray, who is recovering from a strained abdomen, is scheduled for another rehab start on Friday, when he will increase his pitch count to 85.
Giants: RHP Jake Peavy (0-0, 7.20 ERA) makes his 23rd career start against the Rockies. He is 7-7 with a 3.90 ERA lifetime against Colorado.
Rockies: RHP Jordan Lyles (0-1, 13.50) was roughed up for five runs and seven hits in 3 1/3 innings against San Diego in Colorado's home opener on Friday.
Weaver has best start in month, D-backs beat Marlins 5-2
— Luke Weaver pitched scoreless ball into the seventh inning for his best outing in nearly a month, which helped the Arizona Diamondbacks snap a six-game losing streak with a 5-2 win over the Miami Marlins on Monday night.
Giants come through in the pinch, beat Rangers 3-1
— Mauricio Dubon broke a seventh-inning tie with a two-out, pinch-hit single, Alex Wood won for the fourth time in five starts and the San Francisco Giants beat the Texas Rangers 3-1 on Monday night.
Belt rips his eighth HR to open scoring
Brandon Belt goes yard to put the Giants out in front of the Rangers.
Asdrubal Cabrera knocks 2-RBI double vs. Marlins
Asdrubal Cabrera rips a double down the first-base line to score two runs in the Diamondbacks' win vs. the Marlins.
Walsh's big night helps Angels rally for 5-4 win over Astros
— Jared Walsh homered and matched a career high with four hits, Justin Upton also connected and the Los Angeles Angels rallied in the sixth inning to beat the Houston Astros 5-4 Monday night.
Mullins somehow turns pop-up into a triple
Cedric Mullins shows off his speed, storming around the bases for a triple after his pop-up falls into shallow left field.