HOUSTON - Doug Mientkiewicz had his sixth career four-hit game and reached base all five times up, and the Pirates overcame another shaky Ian Snell start to beat Houston, 8-7, this afternoon at Minute Maid Park and complete a three-game sweep of the Astros.

"It was great," manager John Russell said of Mientkiewicz's performance, which included a double and two RBIs. "He's done that a lot for us. He really sparked us."

Snell lasted only three innings and allowed five runs, six hits, three walks an awful pitch count of 85. He worked away from batters relentlessly, left and right, and never appeared confident despite having the same 95-mph zip to his fastball he had enjoyed in his other recent starts.

The Pirates' three-game winning streak is their first since taking six in a row May 6-12, and they finished this road trip 3-4.

"It's a big boost, especially after Colorado," Russell said.

The score was 6-6 entering the seventh, when the Pirates began pecking away at Houston reliever Geoff Geary.

Singles by Ryan Doumit and Xavier Nady, plus a walk to Adam LaRoche, loaded the bases with one out for Mientkiewicz. He ripped a ball through the right side for one run. When Jason Michaels looked as if he would hit into a 6-4-3 double play, Mientkiewicz slid hard into second baseman Kazuo Matsui to prevent that, and another run scored to make it 8-6.

Franquelis Osoria gave the Pirates their first good pitching with two perfect innings in the fifth and sixth.

"Those were big innings," Russell said. "He's starting to get the ball down again. Those two innings might get overlooked, but he really kept us in it. We needed to regroup a little bit, and he let us do that."

Tyler Yates became responsible for the lead in the seventh and gave up a run on three singles and a walk, bailed out by John Grabow.

The Astros threatened off Grabow in the eighth, getting a man to second with one out. But he retired Lance Berkman and Carlos Lee, the Astros' top sluggers, on lazy flyouts.

Damaso Marte recorded his fifth save with a scoreless ninth.

Houston starter Brian Moehler came out with nothing, and the Pirates came out swinging.

Nate McLouth nearly decapitated Moehler with a first-at-bat single, and that was just the start: Freddy Sanchez singled, Doumit hit a sacrifice fly, and Bay launched a ball off the arched fa??ade above left field for the second time in the series to make it 3-0.

It was Bay's 21st home run, matching his total from last season, and it tied Bill Mazeroski for eighth on the Pirates' all-time list. Not including playoffs, of course.

Singles by Nady, Mientkiewicz and even Snell made it 4-0 before the first three outs were recorded.

Snell made that hold up for all of a few minutes: He gave up two walks and a single with his first three batters and, a popup later, longtime Pirates nemesis Mark Loretta worked a 10-pitch at-bat before drilling a two-run single to center. A groundout later brought another, and it was 4-3.

Snell's pitch count for the first: 36. Total length of the inning: 37 minutes.

The Pirates added one in the second on Sanchez's RBI double, but so did the Astros.

Back-to-back doubles by LaRoche and Mientkiewicz made it 6-4 in the third, and Moehler was out in 2 1/3. Again, the Astros matched it in the bottom half.

T.J. Beam gave up another in the fourth, and it was 6-6.

The Pirates now take on another last-place team, the San Diego Padres, beginning tomorrow at PNC Park.

The Pirates had been last in the Central, but this victory overtook Houston.