PHOENIX -- The Astros continued a nine-game road trip through St. Louis, Arizona and Chicago with an uninspiring performance Friday night, dropping a 14-7 decision to the D-backs at Chase Field.

It was a game in which the Astros (62-66) had a 4-3 lead heading into the bottom of the third when two of their young pitchers -- Yorman Bazardo and Wilton Lopez -- were blasted for seven Arizona runs. The loss was their fourth in the past five games.

Bazardo, making just his second start of the season, allowed eight runs and eight hits in his two-plus innings. It was his first loss (0-1), and his ERA ballooned to 9.75.

"I have to make adjustments with my fastball -- be aggressive in the zone -- and I'll be good the next time," Bazardo said. "Otherwise I felt fine. Physically I was 100 percent. I just couldn't throw strikes. I had no command on any of my pitches. Not on my fastball, not on my slider. Not on my changeup. That meant big trouble."

Short on starters at this juncture, Astros manger Cecil Cooper had to use Lopez in long relief on Friday when Bazardo lost his composure in the third inning. He was trying to save Felipe Paulino for a start here on Sunday, but after using four pitchers in the game, Cooper said he had to switch gears.

Wandy Rodriguez will get the start on Sunday with Roy Oswalt tabbed to throw against the Cubs at Wrigley Field on Monday.

"I need to hold back Paulino just in case we need a long reliever [on Saturday]," Cooper said.

The pitching rotation changed after Bazardo opened the third by allowing a leadoff walk and four consecutive D-back hits, including run-scoring doubles by Miguel Montero and Gerardo Parra.

Lopez, just brought up from the Minors on Friday to replace the injured Alberto Arias, made his first Major League appearance with a runner on second and no one out. It wasn't an auspicious debut as Brandon Allen singled, moving Parra to third, and Alex Romero hit a three-run homer. Welcome to the big leagues.

The right-hander also allowed a solo shot to Montero and rookie John Hester's first Major League homer (and hit) -- a two-run pinch-hit bolt. Those two came in a three-run sixth.

Lopez was pelted for six runs on eight hits (including the three homers) in his four innings of work. He threw 92 pitches.

"I thought the kid did pretty well, considering the circumstances," Cooper said. "It was a tough situation to put him in, but I didn't have much of a choice in the matter. He has a chance to be pretty good in the Major Leagues."

As far as Bazardo was concerned, Cooper added: "He's got to learn to command his breaking ball. He's also got to learn to command the zone."

Offensively, the fading Astros had a pair of homers -- a two-run blast by Jeff Keppinger and Hunter Pence's solo shot, his 20th. They added a run-scoring double by Pence and Kaz Matsui's RBI triple. Houston scored its first six runs on five hits off D-backs starter and winner Max Scherzer (8-8), who lasted six innings.

Pence was 2-for-4 on the evening with two runs scored, raising his average to .280.

"He looks like he's starting to come out of it," Cooper said.

Matsui was also 2-for-4 with a double and the triple. He's batting .245.

"I'm just trying to get my head on straight," Matsui said through an interpreter. "I'm just trying to look forward and do something to help my team start to win."