DENVER -- Kris Bryant hit a three-run homer Saturday night as the Chicago Cubs spoiled the major league debut of Jeff Hoffman and beat the Colorado Rockies 9-2.

He took the mound before a crowd of 48,113 -- the Rockies' third sellout of the season -- gave up a single to start the game and then retired nine batters in a row while facing the minimum number of hitters through the third.

But the Cubs, who outhit the Rockies 15-5, broke through for four runs in the fourth and then padded their lead to 7-0 on Bryant's three-run shot in the fifth. It was his 31st home run, giving him the National League lead with one more homer than Colorado's Nolan Arenado.

The win was the Cubs' 19th in their past 23 games. Mike Montgomery pitched very well in his first start for the Cubs after making seven relief appearances, following the July 20 trade that brought him to Chicago from Seattle.

Montgomery walked David Dahl, the first batter he faced, and then retired the next nine batters he faced before walking DJ LeMahieu with one out in the fourth. Montgomery held the Rockies hitless until Nick Hundley homered with one out in the fifth on Montgomery's 60th and final pitch. He was lifted because he had thrown no more than 42 pitches in his relief outings with the Cubs.

Trevor Cahill (3-3) relieved Montgomery and worked the final 4 2/3 innings, allowing four hits and one run.

The loss broke a three-game winning streak for the Rockies, who last won four straight during their season-high tying five-game winning streak July 26-30.

Hoffman (0-1) was the centerpiece acquistion from Toronto when the Rockies traded shortstop Troy Tulowitzki to the Blue Jays on July 27, 2015, for Hoffman and two other minor league pitchers. Hoffman, 23, took the turn in the rotation of Tyler Chatwood, who was placed on the 15-day disabled list earlier in the week with a mid-back strain.

Hoffman gave way to Rusin after throwing 77 pitches, 47 strikes, and allowing seven hits and seven runs, six earned, with one walk and two strikeouts. Hoffman pitched better than his line would indicate. Ben Zobrist's run-scoring double in fourth and Bryant's mammoth 461-foot home run were hard-hit balls. And Hoffman hurt himself with an errant pick-off throw in the fourth and a walk ahead of the homer by Bryant that blew the game open.

But Hoffman gave up four singles in the fourth that were not hit hard and was hurt in the fifth by an error by first baseman Ryan Raburn, whose experienced at that position is limited.

The Rockies scored a run off Trevor Cahill in the sixth on LeMahieu's ground out after Chris Rusin, who relieved Hoffman, and David Dahl began the inning with consecutive singles.

But the Cubs came back to make it 8-2 with a run in the seventh on a two-out single by Miguel Montero, who had singled home two runs in the third and went 3-for-5. Zobrist, who also went 3-for-5, hit his 14th homer in the ninth off Jake McGee to complete the scoring.

Hoffman gave up seven hits and seven runs, six earned, in four innings in his major league debut. He held the Cubs scoreless for three innings before they struck for four runs in the fourth.

Bryant, the third and final batter Hoffman faced in the fifth, hit a three-run homer.

Montgomery made his first start for the Cubs after seven relief outings since they acquired him from Seattle on July 20. He held the Rockies hitless four 4 1/3 innings before Nick Hundley hit his sixth home run, making the score 7-1.

The home run came on Montgomery's 60th and final pitch. Cubs manager Joe Maddon lifted Montgomery at that point because he had not thrown more than 42 pitches in any of his relief appearances since joining the team.

Hoffman gave up a single to Dexter Fowler to open the game but retired the next eight batters until Fowler led off the fourth with a single. He scampered to third when Hoffman threw low to first base on a pick-off attempt and past Raburn.

Bryant won a 10-pitch confrontation with Hoffman and beat the Rockies' shift when he grounded a single through the vacant second-base area.

Anthony Rizzo grounded a single to right that sent Bryant to third and Ben Zobrist lined a run-scoring double to center on Hoffman's first pitch, giving the Cubs a 2-0 lead.

Hoffman retired the next two batters, but Miguel Montero chopped a two-run single up the middle to make it 4-0.

Inexperienced first baseman Raburn muffed Montgomery's bouncer for a two-base error to open the fifth. After Hoffman issued his first walk to Fowler, Bryant blasted his 31st home run.

That gave him the National League lead, one more than Colorado's Nolan Arenado -- as he drove a 3-and-1 fastball an estimated 461 feet to center field to put the Cubs ahead 7-0.

NOTES: Rockies RHP Jeff Hoffman had his contract selected from Triple-A Albuquerque and started Saturday in his major league debut. The Rockies optioned RHP Christian Bergman to Albuquerque. To get Hoffman on the 40-man roster, the Rockies released LHP Jason Gurka. ... Rockies CF Charlie Blackmon was out of the lineup for the second straight game because of a right big toe contusion. ... Rockies RHP Tyler Chatwood (mid-back strain) played catch from 75 feet, the first time he has thrown since going on the disabled list Monday. ... Cubs LHP Mike Montgomery is the ninth pitcher to start this season for the team. The Cubs used five starters in their first 83 games and have used four more in the past 39.