By the Associated Press

Zac Gallen had a career-high 10 strikeouts over six scoreless innings, Christian Walker hit a two-run homer and the Arizona Diamondbacks beat the Colorado Rockies 4-0 in the first game of a doubleheader on Friday.

The 25-year-old Gallen (3-2) has been one of the NL’s top pitchers for much of the season and saved one of his best outings for last, giving up five singles and walking two. He finishes the season with a 2.75 ERA over 12 starts and struck out 82 batters over 72 innings.

Yoan López and Stefan Crichton combined for a scoreless seventh to finish the shutout and further diminish the Rockies’ already minuscule playoff chances.

The Diamondbacks jumped ahead 2-0 in the third inning when Walker crushed a ball down the left-field line that stayed just inside the foul pole. The 29-year-old Walker has been the team’s most consistent hitter this season with a team-high 18 doubles. He also has seven homers and 34 RBIs.

Eduardo Escobar hit a triple later in the third that brought home Kole Calhoun for a 3-0 lead. The ball bounced in and out of the glove of right fielder Charlie Blackmon, who leapt for the catch near the wall.

Colorado’s Antonio Senzatela (5-3) gave up four runs over 4 1/3 innings. He allowed eight hits and four walks while striking out two. Raimel Tapia had three singles for the Rockies.