CHICAGO -- Kris Bryant has already had an outsized share of big hits during the first months of his rookie year.
Now he's developing a flair for the dramatic.
"For the last three or four games, I think I've hit five or six out to the warning track and that's obviously frustrating," said Bryant. "I believe in baseball gods and I believe they pay you back and I guess I got one today."
It was Chicago's 21st come-from-behind victory and 10th walk-off win.
Cubs right-handed reliever Rafael Soriano (1-0) worked one inning for his first career win. Axford (3-4) pitched 2/3 of the ninth inning and took the loss.
"That's the way to win a ballgame," said Cubs right-handed starter Kyle Hendricks, who worked five innings and had no decision. "Giving up the lead was tough, but we're a tough team. We've been in so many ballgames that being down one with our lineup, we weren't too down."
Rockies right fielder Carlos Gonzalez hit two home runs -- including a go-ahead two-run shot -- as the Rockies jumped to a temporary 8-7 lead in the top of the ninth.
Gonzalez, who went 4-for-5 with two runs and four RBIs, clubbed his 20th home run of the season off Soriano with none out in the ninth to cap a four-run inning.
Shortstop Starlin Castro drove in two runs with a go-ahead single in the fourth as the Cubs scored six times that inning and carried a 7-4 lead heading into the ninth.
Hendricks had no decision for the third time in four outings. Left hander Jorge De La Rosa also escaped a loss after working just 3 2/3 innings.
Rockies infielder Daniel Descalso cut the margin to two with a pinch-hit solo home run -- his career first -- to lead off the ninth off Cubs right-hander Jason Motte.
Motte gave up a base hit to center fielder Charlie Blackmon and second baseman DJ LeMahieu's double to right put runners on second and third and forced Motte out.
Soriano entered and got shortstop Troy Tulowitzki to ground into a fielder's choice that scored Blackmon. That set the stage for Gonzalez's go-ahead homer to right on a 1-1 pitch.
Gonzalez also had a two-run, third-inning home run that also drove in LeMahieu for a 2-0 lead.
The homer -- which just cleared the left-field basket -- was the 19th of the season and third in two days for Gonzalez, named Monday as National League Player of the Week.
He went deep twice Sunday in the Rockies' 17-7 win over the Cincinnati Reds.
"It's something to see when he gets rolling, it really is," said Rockies manager Walt Weiss. "He's so talented that he can do anything out there when he gets hot and he's locked in there right now."
Colorado had bases loaded in the fourth and two outs for LeMahieu, who sent a soft grounder to short left that scored first baseman Ben Paulson and catcher Michael McKenry for a 4-0 lead.
The Rockies then tried a double steal, but Cubs catcher Kyle Schwarber fired to Bryant to tag out Blackmon for the third out.
Chicago wiped out the 4-0 deficit by producing six runs while batting around in the last of the fourth.
Colorado's De La Rosa retired nine straight batters to open the game before walking Fowler and Schwarber to start the fourth.
Bryant then broke the hitless run with an RBI single to left that brought home Fowler.
First baseman Anthony Rizzo loaded the bases with a single to center that was mishandled by Blackmon, setting the stage for right fielder Jorge Soler's base hit to right that brought home Schwarber for a second run.
Left fielder Chris Denorfia's fielder's-choice grounder to second scored Bryant, and Castro shook off a slump with a two-run single that plated Rizzo and Soler for a 5-4 Cubs lead.
Second baseman Addison Russell sent Castro home with a base hit to deep left with two out that finally chased De La Rosa.
De La Rosa worked just 3 2/3 innings, allowing six runs on five hits. He walked two while striking out a pair.
"Command got away from in that fourth inning," said Weiss. "He was cruising along up to that point. ... It just happened."
NOTES: Rockies RF Carlos Gonzalez earned NL co-Player of the Week honors after producing 11 RBIs and 25 total bases while tying for the league lead with nine runs and hitting .476. ... From May 29 through Sunday, Colorado SS Troy Tulowitzki has batted .341 -- tied for fourth best in the majors. ... The Rockies send LHP Yohan Flande (0-1, 4.24 ERA) against Chicago RHP Dallas Beeler (0-0, 6.43 ERA) in Tuesday's middle game of the series. ... Cubs president Theo Epstein said Monday that his team is talking potential trades but nothing is close. He said if he does land a big name, it would be for long term. ... Chicago rookie 3B Kris Bryant, just three months into his major league career, already has the second-most popular jersey, according to sales figures from MLB.com.