Chicago ? Sammy Sosa’s struggles were so prolonged that last week he volunteered to drop to No. 5 in the Chicago Cubs’ batting order.

Whether it’s coincidence or not, the Cubs have won eight of nine since Sosa’s demotion, taking back the lead in the NL wild-card race. Sosa’s opposite-field, three-run homer Thursday keyed an 8-3 victory over the Houston Astros.

“He’s swinging a lot better. Today he had the big home run, and that’s the guy we all know,” said teammate Aramis Ramirez, who followed Sosa with a home run of his own in a five-run third.

“He was struggling a little bit, but he’s out there every day giving everything he has,” Ramirez said.

Sosa’s 568th career homer landed just inside the right-field foul pole to give the Cubs a 4-2 lead. Sosa was in a 14-for-75 slump when he connected and needs one homer to reach 30 for a 10th straight season. He declined comment after the game.

“The last week or so he’s been getting a hit a day. He goes unnoticed unless he’s hitting the ball out of the ball park,” Cubs manager Dusty Baker said.

To get back to the playoffs, the Cubs need Sosa to come around, and Mark Prior, too.

Prior (4-3) got his first win in three weeks and his first at Wrigley Field since Game 2 of the NL championship series last October, needing 116 pitches to get through six innings. He missed the first two months this season while on the disabled list because of a sore elbow and Achilles’ tendon.

“I’ve come out of some games with leads a couple of times and it didn’t work out. It doesn’t really matter,” Prior said. “Obviously, it’s nice to win at home, and you should win at home, but as long as we are winning at home, that’s all I care about.”

Prior gave up seven hits, including Jeff Bagwell’s 19th homer, and escaped a second-and-third, no-outs jam in the sixth.

Chicago's Nomar Garciaparra, left, congratulates Sammy Sosa after Sosa hit a three-run home run against Houston. The Cubs defeated the Astros, 8-3, Thursday in Chicago.

“I don’t think he was as sharp as we’ve seen him in the past,” Houston’s Brad Ausmus said. “He left his breaking ball up in the zone, and you could tell he was getting upset with himself. Unfortunately for us, we didn’t fair any better, even when he has scuffling.”

The loss was just the third in 11 games for the Astros, who stranded 12 runners and fell seven games behind the Cubs.

“We’re in a situation where we really have to win every day,” Ausmus said.

Braves 6, Rockies 4

Atlanta — Mike Hampton helped himself with an RBI single, and Atlanta pushed its NL East lead to a season-high 9 1/2 games with a win over Colorado. The Braves completed a three-game sweep and won their fourth in a row overall. Colorado has lost four straight.

Rookie Charles Thomas drove in two runs, and every Atlanta starter collected at least one hit. The Braves finished with 11 hits — they’ve reached double digits in hits in six straight games.

In 56 games since June 23, when the Braves were six games under .500 at 32-38, Atlanta is 41-15.

Padres 10, Mets 3

New York — Adam Eaton shut down New York through seven innings to win his seventh straight road start, and San Diego completed a four-game sweep of the Mets. It was the fifth straight loss for the Mets, who never held a lead during the series and were outscored 26-8, with half their runs coming in the ninth inning. New York managed just 22 hits in the four games. Eaton (9-11) retired 19 of his last 21 batters.

Dodgers 10, Expos 3

Montreal — Adrian Beltre hit his major-league-high 41st homer, and Eric Gagne was cheered wildly in what likely was his final game in his hometown. Despite a seven-run lead, the Dodgers used Gagne in the ninth inning. The Montreal native, pitching at home for the first time since winning last year’s NL Cy Young Award, drew attention when he started warming up and the crowd of 18,520, the Expos’ third-highest at home this season, gave him a standing ovation when he pitched. He retired three in a row after a leadoff walk.

Reds 1, Cardinals 0

Cincinnati — Aaron Harang threw a three-hitter for his first career complete game, and Sean Casey homered to lead Cincinnati over St. Louis. Chris Carpenter (13-5) also pitched a three-hitter and struck out 11 for the Cardinals, but he wound up with a tough loss. Casey hit the first pitch from Carpenter into the right-field bullpen with two outs in the sixth inning for his 21st homer. Cincinnati took two of three from the Cardinals, who had won eight straight series.

Giants 5, Marlins 0

Miami — Brett Tomko pitched a four-hitter for his first career shutout, and San Francisco beat Florida. Wrapping up their first visit to South Florida since being eliminated in the playoffs last October, the Giants took the finale of the three-game series. Tomko (7-6) made sure the crowd of 29,638 had little to cheer about. He threw his first complete game this season, allowing four singles and one walk while striking out four. Tomko improved to 5-0 in seven starts against the Marlins.