DENVER -- Colorado manager Walt Weiss was well aware his team would be in a bind if it had to play extra innings. Mark Reynolds rescued the Rockies with a clutch drive.
Reynolds hit a two-run homer with two outs in the bottom of the ninth inning for a 9-7 victory over the Arizona Diamondbacks on Sunday.
Carlos Gonzalez launched a grand slam, and Trevor Story and Charlie Blackmon also went deep for the Rockies, who earned a split of the four-game series.
It might turn out to be a costly win. Story sustained a bruise on his right middle finger when he was hit by a pitch leading off the ninth. He stayed in the game and later said X-rays were negative.
"Everything's OK, just bruised really bad," the rookie shortstop said. "It's hard to move, real swollen. A lot of ice and we'll wrap it up."
The Rockies had already lost All-Star second baseman DJ LeMahieu to a bruised left knee. LeMahieu was hurt making a sliding attempt at Paul Goldschmidt's two-run single in the sixth inning and left the game.
LeMahieu will have an MRI on Monday, the Rockies said.
Weiss said Story wouldn't have played defense in the 10th, leaving Colorado without its starting middle infield, no bench players and a limited bullpen.
"We knew if we went extra innings we were in trouble," Weiss said.
Reynolds made sure that didn't happen. With Story on first, the strikeout-prone slugger drove a 2-1 fastball from Silvino Bracho (0-1) an estimated 464 feet to left-center for his eighth home run of the season.
"It was my first walk-off homer so it's probably the timeliest one I've hit," he said. "I knew he didn't want to walk me and put a guy in scoring position. I knew he was going to throw a strike and he grooved a fastball."
It was Colorado's first walk-off win since Sept. 26, 2015.
Carlos Estevez (2-5) struck out two in a hitless inning for the victory.
Goldschmidt had two hits and four RBI for Arizona. He has reached base in 48 straight games against the Rockies, a mark that ties him with Mike Piazza, who did it from 1995-99.
"Oh good, send me a trophy. I don't care, guys," Goldschmidt said. "I mean, 48 -- that's like three years ago. Who cares?"
Arizona led 3-1 after three innings and increased the margin to 5-1 on Goldschmidt's two-run triple in the fourth. The Rockies rallied in the fifth to take a 6-5 lead on Gonzalez's grand slam off starter Patrick Corbin.
It was Gonzalez's 16th homer of the season and fifth career slam.
Goldschmidt gave the Diamondbacks the lead again with his two-run single off Rockies starter Chad Bettis. Story answered with a solo homer in the seventh, his 19th, to tie it.
The Diamondbacks finished 7-3 on their road trip.
"That's just the way things break in this ballpark," manager Chip Hale said of Colorado's four home runs. "You have to live with it. We had a real good road trip. I'm happy with the way these guys performed. The effort was relentless."
Arizona finished with 56 hits to set a club record for a four-game series. The previous best was 53, done twice against Colorado. The last time it happened was 2012.
The teams combined for 109 hits in the series.
Diamondbacks: SS Nick Ahmed is on baby watch and did not start. Hale said Ahmed had an afternoon flight to Phoenix booked in case his wife went into labor, but it proved unnecessary. Ahmed entered as a pinch-hitter in the seventh and remained in the game. ... Hale said Chris Owings (left foot plantar fasciitis) "is not where we thought he'd be" in his rehab. Hale expressed hope that Owings could be back by the end of the Diamondbacks' upcoming 10-day homestand.
Rockies: LHP Jake McGee (sprained left knee) threw a bullpen. He is scheduled to go on a rehab assignment with Double-A Modesto to pitch an inning Tuesday and Thursday.
Diamondbacks: LHP Robbie Ray (4-6, 4.59 ERA) takes the mound for the first of a three-game series against the Phillies on Monday. Ray won in Philadelphia on June 17.
Rockies: RHP Jon Gray (4-3, 4.80 ERA) opens a three-game series against Toronto on Monday. Gray left his last start at Yankee Stadium after five innings due to arm fatigue.