"It's as good as I've seen Juan this year," manager Walt Weiss said.
Fowler got mobbed by teammates after his hit, but it was Gonzalez who did the dirty work to get the Rockies to the 10th inning. The left fielder made two big catches near the wall and came through with a two-strike, two-out double in the ninth to tie the score.
It was his only hit of the day but it helped the Rockies gain a split of the four-game series.
"I was battling the whole game offensively," Gonzalez said. "When you're having a tough game offensively you have to go out there and keep the game close and help the pitchers as much as you can."
Three of the games were won in the winning team's last at-bat. Sunday, it was Colorado's turn.
Rex Brothers (2-0) pitched the 10th for the victory.
Fowler then singled up the middle off Joe Thatcher, who came on to face Colvin, to give the Rockies their sixth walk-off win this season and second of the series.
"I was just trying to make a pitch, keep it down," Thatcher said. "He got a better piece of it than I would have liked for him to."
Fowler got the game-winning hit after the Rockies rallied against closer Luke Gregerson in the ninth. Colvin's RBI single made it 7-5 and Gonzalez tied it with a two-run double down the right-field line on Gregerson's third straight slider.
"He threw me another one on the outside corner, I tried to stay patient and let it get deep," Gonzalez said. "It was the perfect pitch to hit to right field."
Ross came on and retired Nolan Arenado to send the game into extra innings.
Gonzalez's game-tying double nearly overshadowed his defense. The Gold Glove outfielder made two fine catches, one in the fifth on Kyle Banks' drive to the top of the wall to temporarily preserve the perfect game and another in the sixth to end a rally and save two runs.
"He's a phenomenal athlete," Weiss said. "A huge double to tie the game up. Big-time performance by CarGo."
It was also a big-time performance early by Nicasio, who was untouchable through the first five innings. He struck out seven and had only one three-ball count, to Will Venable in the second inning.
Maybin grounded out to start the sixth before the Padres broke through. Hundley hit a 2-2 slider into the left-field bleachers to end the drama, and the 33,668 fans at Coors Field gave Nicasio an ovation as Hundley circled the bases.
"I hung a slider," Nicasio said. "I didn't think about the no-hitter, only that I missed the pitch. If I put my slider in the dirt maybe he strikes out."
With the perfect game gone, Nicasio appeared to lose his rhythm. The next three batters singled to make it 4-2 before Gonzalez made a running catch of Venable's liner to end the inning.
Edgmer Escalona came on in the seventh and allowed a solo home run to Maybin and a two-run, pinch-hit homer to Kotsay that gave the Padres a 5-4 lead.
They were the first homers of the year for both players.
"Playing here the game's never over," said Padres second baseman Jedd Gyorko, who left in the 10th with a right groin strain. "Their guy has a no-hitter through five and by the seventh inning we have the lead."
The Padres scored two more off reliever Matt Belisle in the eighth to make it 7-4.
San Diego starter Clayton Richard had a rough start to his day even before he took the mound.
A few hours before the game, Richard, Hundley and pitching coach Darren Balsley had a closed-door meeting in the clubhouse manager's office to go over the game plan for the afternoon. When they were done, the door was jammed and couldn't be opened.
After clubhouse personnel tried unsuccessfully to unlock the door with several sets of keys, Richard, Hundley and Balsley removed the pins from the hinges and the door was pushed open from the outside.
Things didn't get much better for Richard when he took the mound. He gave up a two-run homer to Tulowitzki in the first inning and two more runs in the third on a groundout by Gonzalez and a triple by Arenado to make it 4-0.
Richard settled down after that, retiring 10 of the last 12 batters he faced. He allowed four runs on eight hits, struck out three and walked one in six innings.
"I thought I threw well for the most part," he said. "A bad pitch to Tulo that came over the plate, but really other than that it was just baseball."
Escalona left the game with right triceps soreness. He is scheduled to have an MRI on Monday and the Rockies said the results will be known Tuesday. ... San Diego SS Everth Cabrera extended his hitting streak to a career-high 10 games. ... Rockies OF Michael Cuddyer was out of the lineup for the third straight game with a strained rib cage muscle. Weiss said Cuddyer has improved since getting injured in the 12th inning Thursday and with a day off Monday thinks there is a chance the veteran will play the opener against Washington on Tuesday. ... San Diego closer Huston Street (left calf strain) will pitch a simulated game Monday. He is eligible to come off the 15-day DL on Friday. ... Padres RHP Jason Marquis (7-2) will pitch Monday's opener of a three-game series against Atlanta.