PHOENIX -- Yasmany Tomas, the Arizona Diamondbacks' unexpected home run king, kept his season-long power surge going Monday.

Tomas hit an opposite-field grand slam to right-center field in a four-run sixth inning, and the Diamondbacks earned a 12-9 victory over the Colorado Rockies at Chase Field despite squandering an early five-run lead.

Tomas had four hits, five RBIs and three runs, his slam pushing the D-backs in front 10-9. He has 29 homers, one more than Jake Lamb for the team lead.

"That ball jumped out of here, but he had good at-bats all night," Arizona manager Chip Hale said.

Tomas had 19 homers as a rookie last season after signing a six-year, $68.5 million free agent contract.

"Was he going to be a big home run guy?" Hale said. "We thought he was going to be more gap-to-gap. He has it in him. I didn't think it would come this quickly."

Brandon Drury and rookie Mitch Haniger hit bases-empty homers in the seventh inning as the Diamondbacks (59-84) broke a six-game losing streak. Haniger's homer was the first of his career.

Drury had four hits and scored three runs, rookie Kyle Jensen had two hits and three RBIs, and Lamb had two hits and an RBI for the D-backs.

"A lot of good at-bats by our offense all night from first pitch on," Hale said. "Falling behind after getting a lead, the guys just rallied."

Colorado cleanup hitter Carlos Gonzalez had four hits, including three doubles, and drove in three runs. Charlie Blackmon and Nolan Arenado added three hits apiece for the Rockies (69-75), who had won three of five.

Daniel Descalso homered and had three RBIs for Colorado. Descalso has six homers, three in the past four games against Arizona.

Arizona led 5-0 after three innings when right-hander Shelby Miller retired the first nine batters he faced.

Colorado posted three-run rallies in the fourth, fifth and sixth innings for a 9-6 lead, knocking Miller out after five innings.

"They got some clutch hits and we got some clutch hits," Colorado manager Walt Weiss said. "They got a few more."

Drury, Paul Goldschmidt and Welington Castillo singled with two outs in the sixth inning before Tomas hit an opposite-field homer to right field off Jordan Lyles (4-5).

"With Tomas, I tried to go down and away, but I didn't make my pitch," Lyle said. "He put a good swing on it. It was just where I wanted to stay away from is where it ended up."

Right-hander Randall Delgado (4-1) retired one of the four batters he faced in the sixth inning for the victory.

Daniel Hudson pitched a scoreless ninth inning for his third save.

Jensen had an RBI single in the second inning and a two-run single in the third, driving in Tomas both times, as Arizona took a 5-0 lead off left-hander Tyler Anderson, who went 4 1/3 innings.

The first four hitters in the Colorado order -- Blackmon, DJ LeMahieu, Arenado and Gonzalez -- reached base in the fourth, fifth and six innings. Gonzalez drove in three runs with his first two doubles when the Rockies went ahead.

Those four batters finished a combined 12-for-19 with eight runs and five RBIs.

"Charlie and DJ have been getting on base and doing their thing most of the year, if not all year," Weiss said. "When they do that Nolan and Cargo are swing the bats, we will score some runs like we did tonight. But you have to keep them from scoring, too."

NOTES: Arizona CF A.J. Pollock (groin) was expected to take batting practice Monday or Tuesday, manager Chip Hale said, he should return before the end of the regular season. Pollock was removed Friday after tweaking his groin while running out a fly ball in the first inning. ... Arizona SS Chris Owings was given a start off after playing in 40 consecutive games since July 29, although he entered as a defensive replacement in a double switch in the eighth inning. Owings has hit .310 with 11 doubles, five triples and seven stolen bases in 167 plate appearances in the past 40 games, starting 39. ... Colorado LF Gerardo Parra (hamstring strain) did not play Monday but is expected to return during the three-game series in Arizona that began Monday, manager Walt Weiss said. ... Arizona RHP Rubby De La Rosa will be on a 60-pitch limit in his Wednesday start against Colorado, and RHP Braden Shipley is expected to follow him into the game.