Before Friday night's game, rookie third baseman Nolan Arenado was getting the business, and how, from irascible veteran Todd Helton in the Rockies' clubhouse.

Arenado took it in stride, laughing and doing his best to dish it back.

Then he went out and beat the San Diego Padres with a solo home run in the ninth inning off reliever Joe Thatcher, lifting the Rockies to a wild 10-9 victory.

"Right when I hit it, I knew it was out," Arenado said. "That was a big moment for me, to be able to help the team win."

The first walk-off homer of Arenado's career and the first walk-off homer of the season for Colorado sent a Coors Field crowd of 30,477 home happy and feeling wiped out.

"It was a big relief," said Rockies manager Walt Weiss. "It was a crazy game and Nolan had to come up with a huge hit."

The victory came close to becoming an infamous defeat for the Rockies.

The seventh inning was spectacularly bad for Rockies reliever Rob Scahill. Handed a 9-4 lead, Scahill gave up five runs and four hits, including back-to-back home runs by Carlos Quentin and Jedd Gyorko. He failed to get an out before leaving to a cascade of boos.

The Rockies got a scare in the sixth when Carlos Gonzalez appeared to injure his knee in the batter's box on a groundout to short. He hobbled up the first-base line and into the dugout, but went back out to play left field in the seventh. Later in the inning he was removed from the game, replaced by Jonathan Herrera. Before he departed, CarGo had two triples and three RBIs.

With their offense cranking from the outset, the Rockies had leads of 3-0 after one inning, 8-2 after two and 9-3 after three. A two-run double by Helton and a two-run triple by Gonzalez were the biggest blows against San Diego starter Edinson Volquez.

Troy Tulowitzki, who had an RBI single in the first inning, finished 3-for-4, raising his average to .348. Dexter Fowler, a day after he was benched because of a migraine, led off the first with a triple and finished the game hitting .292.