SAN DIEGO -- If Major League Baseball had given the San Diego Padres the option of omitting one inning from their 7-3 loss to the Arizona Diamondbacks on Wednesday at PETCO Park, they'd easily throw out the fifth.

Minus that one inning, the game might still be going with the score tied at 3. Instead, the Padres will have to marinate over another defeat they let slip away in one attempt to get three outs.

The Diamondbacks' Alex Romero doubled and advanced to third on a throwing error by Chase Headley to start off the fifth. Pitcher Dan Haren stepped up the plate and hit a grounder down the third-base line as Romero charged home. Padres' third baseman Kevin Kouzmanoff tried to prevent the run but catcher Josh Bard misplayed the ball and it scurried past him. Romero scored.

"I don't think any team can afford to make errors and it showed up in that inning," Padres manager Bud Black said.

Chris Young hit a double that scored Haren, Orlando Hudson walked, Conor Jackson singled and Chad Tracy hit a two-run single. The Diamondbacks put up four runs in an inning aided by two Padres errors.

Padres starter Cha Seung Baek, who allowed five runs (four earned) on eight hits with five strikeouts and one walk in 4 1/3 innings, threw 31 pitches in the inning and was pulled for Cla Meredith for the last out.

The score went from 3-1 Padres, to 5-3 Diamondbacks. Arizona never looked back.

"It was one of those games where we didn't get the breaks," Bard said. "I think there were some times defensively where we didn't play as well as we could've, myself included. We just have to do a better job behind him."

Before the fifth inning, the game was in the Padres' control.

Jody Gerut opened the bottom of the first inning with his second leadoff home run of the season and his seventh overall on a 2-2 delivery from Haren. Luis Rodriguez and Adrian Gonzalez both singled to center, and Kouzmanoff hit a sac fly to score Rodriguez. As the top half of the first inning closed, the Padres were up 2-0 on one of the hottest pitchers in the league.

"You're talking about an All-Star pitcher two years in a row," Black said. "Jody put a good swing on a ball, Luis got a hit, Gonzo got a hit and Kouz hits a sac fly. We put a little pressure on him early."

The Diamondbacks got half of that back in the bottom of the inning on consecutive doubles by Chad Tracy and Mark Reynolds who went a combined 4-for-8 with four RBIs in the game.

The Padres added one more run in the fourth on three straight singles by Gonzalez, Kouzmanoff and Bard. But Gonzalez would be the last Padres player to cross the plate.

Haren got back in a rhythm as the game progressed and extended his streak of seven-inning outings to eight games as he went seven innings and gave up up three runs on seven hits with six strikeouts on 104 pitches.

"He might not have been totally on top of his game but he sort of got it together in the middle innings and showed why he's the pitcher he is," Black said. "We couldn't quite break through in the middle part of the game."

The fifth inning got the Diamondbacks back in it and back-to-back home runs by Reynolds and Chris Snyder off Padres reliever Bryan Corey gave the Diamondbacks a 7-3 lead that would never be threatened.

"Seems like every time I make a mistake, I'm paying for it," Corey said. "I might be a little bit snake bit right now, I don't know. But we are major league pitchers and they are major league hitters. You make mistakes all the time but you don't always pay for them."