"For 3 1/3 innings last night, Walter Silva was perfect and the Padres were flawless.

Then it all fell apart in perhaps the Padres' worst inning of the season.

Houston sent 10 hitters to the plate against Silva in a six-run fourth that resulted in a 7-1 Astros victory before 16,670 at Petco Park.

For the third straight game, Silva departed with a bad pitching line. This time, however, it wasn't entirely the fault of the 32-year-old product of the Mexican League.

Half the six runs charged to Silva were officially unearned - thanks to a three-run throwing error by third baseman Chase Headley on a two-out grounder.

And the Padres, who managed just five hits, could have limited the damage further by making a couple of other plays.

"I liked the way Walter bounced back from his last start," said Padres manager Bud Black, referring to last Friday night's outing in Texas when Silva gave up nine runs (eight earned) on seven hits and four walks in 2 1/3 innings.

"His pitches looked a little crisper tonight. He pitched better."

Early on, Silva looked invincible.

After striking out the first two Astros he faced, Silva retired five straight hitters on ground balls and allowed only one ball to reach the outfield on his first time through the order.

But Houston struck for four straight hits after Michael Bourn popped out to Adrian Gonzalez to start the fourth - opening the door on the six-run inning.

Silva's final line last night was six runs (three earned) on five hits over four innings, giving him a 10.79 ERA since he was recalled from Triple-A Portland on June 20 to take the injured Chris Young's slot in the rotation.

"The first couple innings I was in command of my pitches," said Silva.

"The one inning changed everything, but that's the game. You can see the difference in this game and the last game I threw.

"But sometimes you pitch good and don't win. Sometimes you pitch bad and get the win. I'll just keep pitching hard until I get a break.""