CINCINNATI (AP) _ When Kazuo Matsui singled home a pair of runs with two outs in the fourth inning, Houston Astros manager Cecil Cooper scribbled something in his black-covered notebook.

"On my pad, I wrote, 'One two-out base hit,'" Cooper said. "Then I wrote, 'Two two-out base hits.'"

He kept going, all the way up to six.

The Astros scored seven runs in the fourth inning _ all on two-out hits _ and rolled to their fourth straight victory Wednesday night, 9-3 over a struggling Cincinnati Reds team that's trying to remake itself.

Houston has won four in a row for the first time since last May, getting 36 runs out of a lineup producing top-to-bottom.

"You've just got to have good at-bats," said Darin Erstad, who had the second two-out hit of the inning. "When you have good at-bats guy after guy, it puts a lot of pressure on the other team. We've been doing a good job of that."

Ken Griffey Jr. hit his 597th career homer off Chris Sampson (1-2), the only bright moment for the Reds, who changed general managers before the game. Walt Jocketty took over for Wayne Krivsky, a show of impatience by team owner Bob Castellini.

Jocketty watched from an upstairs booth as the Reds lost for the ninth time in 12 games. At 9-13, they're off to their worst start in five years.

If right-hander Bronson Arroyo (0-3) doesn't get turned around, the outlook is dreary.

The Astros knocked Arroyo out of the game by sending 11 to the plate in the fourth inning for seven runs. Matsui, who has delivered three pivotal hits since he returned from the disabled list, had the first of six straight off Arroyo and reliever Mike Lincoln.

Arroyo gave up 10 hits, a walk and eight runs in 3 2-3 innings, raising his ERA to 7.56. His fastball was missing a few miles per hour, but Arroyo couldn't figure out why.

"I know he's going crazy," manager Dusty Baker said. "We're trying to help him figure it out. Right now, we don't have an answer. Before, he had better velocity, but he didn't have the location. Plus, when he gets a ball up or makes a mistake, they're not missing it."

Since Arroyo got a contract extension last year that will bring him an additional $25 million through 2010, Cincinnati's No. 2 starter has gone 9-18. He's not sure why he's gotten off to such a slow start this year.

"I feel great," Arroyo said. "I've watched video, but there's nothing to see. I'm just getting beat, man. That's all there is to it. There's nothing else to say."

A day after the Astros set a season high for runs in an 11-7 win over the Padres, their lineup continued to string hits together. Every starter except Sampson had at least one.

Erstad and Hunter Pence led the way with three hits apiece.

It was another impressive showing by the Astros in a ballpark where they have dominated lately. They're 9-1 at Great American Ball Park during the last two years, and 25-15 since it opened in 2003.

The big, early lead helped Sampson rebound from the worst start of his career. The right-hander retired only two batters last Friday in Colorado, giving up six runs and six hits in an 11-5 defeat.

Ahead 9-1 in the fourth, Sampson could challenge a lineup that has struggled all month, a big factor in Krivsky's firing. He allowed eight hits and two runs in seven innings.

"In my last game, I felt good _ maybe too good," Sampson said. "I had all of my pitches working tonight. I tried to convince myself when I went out there that it was 0-0. I didn't want to make stupid mistakes and throw pitches right down the middle of the plate."

Griffey's solo homer in the first inning was his first in a span of 22 at-bats and left him three shy of joining Barry Bonds, Hank Aaron, Babe Ruth, Willie Mays and Sammy Sosa with 600 homers.

It was Griffey's first homer on a seven-game homestand that concludes Thursday. The Reds will play nine games in San Francisco, St. Louis and Atlanta. Griffey hit his 200th, 300th, 400th and 500th homers in road games.

Notes:@ The seven-run inning was Houston's biggest since it scored seven in the fourth inning last July 29 against San Diego. The Astros designed for assignment infielder Tomas Perez and called up RHP Jack Cassel to start on Thursday. Pence extended his hitting streak to six games. Griffey's 199th homer with the Reds moved him ahead of Barry Larkin for eighth place on the franchise list. Griffey came to his hometown team in a trade with Seattle before the 2000 season. 3B Edwin Encarnacion extended his hitting streak to a career-high 13 games with a solo homer in the ninth.

Copyright 2008 The Associated Press.