Zac Gallen pitched seven shutout innings, lowering his ERA to 0.95 in five starts this season, to help the Arizona Diamondbacks beat the Colorado Rockies 4-0 on Sunday in Phoenix.

Gallen (2-0) allowed five hits with seven strikeouts and no walks. He retired the last seven batters he faced.

Relievers Noe Ramirez and Joe Mantiply did not allow a hit or walk in the last two innings. Ramirez struck out the first batter in the ninth, and Mantiply struck out the last two batters.

Arizona, victorious in nine of its past 12 games, won two of three against the Rockies behind starting pitchers Merrill Kelly, Zach Davies and Gallen. They combined to allow only one earned run in 22 innings, with 15 hits allowed, four walks and 21 strikeouts.

Gallen has issued only four walks in 28 1/3 innings this season while posting 26 strikeouts.

The Diamondbacks' No. 1 prospect, center fielder Alek Thomas, made his major league debut and got his first career hit in the fifth inning. He doubled to lead off the inning and moved to third on a sacrifice bunt by fellow rookie Jose Herrera, a catcher.

After designated hitter Cooper Hummel -- another rookie -- reached on a walk, Colorado starter German Marquez (0-3) tried to pick Hummel off at first base but committed a throwing error.

Thomas ran home to put Arizona ahead 4-0.

Colorado had its lone scoring threat against Gallen in the first inning after Yonathan Daza singled and Charlie Blackmon doubled with one out. They were left stranded after Gallen struck out C.J. Cron and got Ryan McMahon to ground out.

After Arizona was retired in order in the first inning, the Diamondbacks rallied for three runs in the second after Ketel Marte doubled off Marquez.

Geraldo Perdomo walked, and Nick Ahmed followed with a single that scored Marte and moved Perdomo to second.

With two outs, Herrera recorded his first career RBIs with a double that brought home Perdomo and Ahmed to put Arizona ahead 3-0.

Marte went 3-for-4 with a run to improve his batting average to .206.

--Field Level Media