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SAN DIEGO -- The heart of the San Diego Padres' lineup came through in a big way Friday night.

Carlos Quentin, Yasmani Grandal and Chase Headley hit home runs as the Padres powered past the Colorado Rockies 9-5 in the opener of a three-game series.

An improved San Diego offense has propelled the club to four straight wins and six of seven as the Padres have scored seven or more runs in five of their past seven games.

"I think we're having some quality at-bats," Quentin said. "We're getting on base consistently throughout the lineup. Guys are causing havoc on the bases and having good at-bats."

Jason Marquis (3-5) pitched five innings for his second straight win for San Diego. Huston Street retired the side in the ninth to secure the win and has not allowed a run in his past 13 appearances, spanning 11 2/3 innings.

Marquis allowed five runs -- three earned -- on nine hits. The former Rockies pitcher struck out two and had lost four straight before his past two starts.

"Our guys picked up Jason, but he hung in there," Padres manager Bud Black said. "Our offense picked up our defense. The guys are picking each other up across the board, and that's what it takes to win."

Carlos Gonzalez hit his second career grand slam for the Rockies, who have lost five of six.

"He battled a lot especially after Gonzalez hit the grand slam," Grandal said of Marquis. "I think he was frustrated that some of his pitches were missing the zone."

Quentin's solo homer was part of a three-run second that gave San Diego a 3-0 lead, but Gonzalez's slam in the third put Colorado up 4-3. After going 25 games without a home run, Gonzalez has homered in his past two.

The Padres came right back in the bottom of the third with Chris Denorfia's two-run triple and Grandal's two-run homer against Drew Pomeranz (1-5). Grandal also doubled in the first and had three RBIs.

"That's sort of how you draw it up," Black said of the production in the middle of the lineup. "Those guys did a nice job."

Pomeranz allowed a career-high seven runs on nine hits over three innings. The left-hander struck out three and matched his shortest outing of the season.

"I really don't think I made that bad of pitches," Pomeranz said. "My velocity was down a lot tonight. The home run to Quentin was a bad pitch. Grandal hit the ball from his shoelaces. I was a little off tonight for whatever reason."

Andrew Brown's sacrifice fly in the fifth cut the Rockies' deficit to 7-5.

"We've been here before," Rockies manager Jim Tracy said. "Once again, plenty to talk about offensively. We didn't pitch in the early part of the game but got back into the game. You surrender seven runs prior to getting three outs in the third inning, you're running uphill."

Three relievers combined to hold the Rockies scoreless before Ramon Hernandez and Josh Rutledge represented the tying runs at second and third in the eighth. But Joe Thatcher struck out pinch hitter Jason Giambi to end the threat.

"That's a big out, a big spot in the game," Black said. "You look at different teams, and this is one team where they've got Giambi over there every night. We had Joe out there for that purpose."

Headley hit a solo shot, his 11th, in the eighth after Logan Forsythe's sacrifice fly scored pinch hitter Mark Kotsay.

Game notes

Rockies C Wilin Rosario left the game in the second with a lower left leg injury. Rosario was hurt on a wild pitch and was slow to retrieve the ball after it bounced past him. Hernandez entered in Rosario's place. ... Both teams observed a moment of silence before the game to honor the victims of the movie theater shooting in Aurora, Colo. "I think when you experience something like that, we're just playing a baseball game, and it pales in relation to what a number of people are going through right now as we sit here," Tracy said. ... Padres CF Cameron Maybin missed a second straight start with wrist soreness. Maybin pinch ran and stole a base in the eighth, and is expected to rest the injury for a few more games. ... Jeff Francis (2-2, 4.76 ERA) will pitch for Colorado in the second game of the series, against Kip Wells (1-3, 2.82).