Paul Beaty, Associated Press
Chicago Cubs' Aramis Ramirez watches as he launches his second three-run homer against the Washington Nationals on Saturday.

CHICAGO — Ryan Dempster has a shot at 20 wins. He's much more focused on the Chicago Cubs' 100-year championship drought.

Dempster matched a career high with his 15th victory and Aramis Ramirez hit a pair of three-run homers, leading Chicago over the Washington Nationals 9-2 on Saturday.

Mark DeRosa homered in his third straight game and Alfonso Soriano added an RBI double for the Cubs, who improved to 48-19 at Wrigley Field. Dempster (15-5) allowed one run in 7 1-3 innings.

Converted to a starter this season after he was Chicago's closer last year, Dempster improved to 12-2 in 16 home starts. The right-hander, who predicted in spring training that the Cubs would win the World Series for the first time since 1908, is not putting any emphasis on reaching 20 wins.

"I don't know. I'm not worried about that. It's a great personal accomplishment, but my motivation is one reason and one reason only and that's to get to the playoffs and win the World Series," Dempster said. "I will take 15 wins and a World Series and I'd be the happiest player in baseball."

On a muggy day, Dempster retired 13 of 14 batters between the second and sixth in conditions similar to his previous win Sunday at Florida.

"It was as hot today as it was in Florida. At least as humid. It was sticky out there," Dempster said. "But I felt like I got stronger as the game went on. I was able to maintain myself."

The Cubs, who have the best record in the NL at 79-50, bounced back from Friday's 13-5 loss to the struggling Nationals by getting 13 hits and another impressive performance from Dempster, who also won 15 games for the Marlins in 2001.

"Outside of Brandon Webb, there aren't too many people pitching better than he is," Cubs manager Lou Piniella said.

Dempster scattered eight hits, struck out four and walked one, sending the Nationals to their 13th loss in 15 games.

"He's been our MVP," DeRosa said. "I know he set a personal best, but he is not satisfied. He is one of those guys that has busted his tail to put himself in this position. He's been just unbelievable for us."

After stranding eight runners through the first three innings, the Cubs didn't let Washington starter Odalis Perez off the hook in the fourth. With one out, Perez walked Soriano and he advanced to third on Ryan Theriot's bloop single. Derrek Lee followed with an RBI single and Ramirez homered to put Chicago up 4-0.

Ramirez is 7-for-15 against Perez with three home runs and eight RBIs.

PHILLIES 9, DODGERS 2: At Philadelphia, Pat Burrell homered and matched his career high with five RBIs, and Cole Hamels pitched effectively with some overdue run support to lead the Phillies. Burrell put the Phillies ahead with his 30th homer. Philadelphia won for the fifth time in six games to move within 1 1/2 games of the NL East-leading New York Mets. Hamels (11-8) went seven innings, allowing two runs and five hits while striking out five and walking none.

ASTROS 8, METS 3: At New York, Lance Berkman hit a three-run homer, Brandon Backe brought his best stuff to the mound for Houston. Berkman finished with three hits and four RBIs. David Newhan added his first homer of the season and Miguel Tejada drove in a pair of runs for the Astros. Backe (8-12) lasted seven-plus innings, allowing three runs and five hits.

BREWERS 6, PIRATES 3: At Milwaukee, Ryan Braun homered, doubled and drove in three runs, leading Jeff Suppan and the Brewers past Pittsburgh for their third straight victory. The NL wild-card leaders moved to 20 games over .500 for the first time since finishing the 1992 season 92-70 in the AL East. Suppan (9-7) earned his fourth consecutive win.

BRAVES 8, CARDINALS 4: At St. Louis, pinch-hitter Greg Norton delivered a tiebreaking single with two outs in the eighth inning, and Atlanta beat St. Louis to snap a six-game losing streak. Albert Pujols homered and drove in three runs for the Cardinals, who dropped 3 1/2 games behind Milwaukee in the wild-card race.

DIAMONDBACKS 7, MARLINS 1: At Phoenix, Yusmeiro Petit pitched six solid innings and Arizona padded its NL West lead, getting home runs from Chris Young and Miguel Montero in a victory over Florida. Petit (3-3) allowed two hits and struck out six, matching season bests. The Diamondbacks had 12 hits and stretched their division lead over Los Angeles to three games.

GIANTS 4, PADRES 3: At San Francisco, Rich Aurilia tripled in the go-ahead run with two outs in the bottom of the eighth, and Barry Zito (8-15) allowed four hits in eight innings to help the Giants match their season-best four-game winning streak. Brian Wilson worked a perfect ninth for his 34th save in 37 chances.

ROCKIES 7, REDS 6: At Denver, Matt Holliday hit a three-run double that highlighted a seventh-inning rally, sending Colorado over Cincinnati. Jay Bruce and Chris Dickerson homered and Joey Votto had three hits for the Reds. Luis Vizcaino (1-0) won in relief and Brian Fuentes pitched the ninth to earn his 25th save in 29 chances.

American League

RAYS 5, WHITE SOX 3: At Chicago, Carlos Pena's two-run single capped a four-run eighth inning, and surging Tampa Bay increased its AL East lead to 5 1/2 games over the second-place Red Sox by ralling past the White Sox. Chicago's Jermaine Dye hit two solo homers.

BLUE JAYS 11, RED SOX 0: At Toronto, Vernon Wells hit two home runs, Marco Scutaro added a solo shot and the Blue Jays roughed up Jon Lester in a rout of Boston. Wells went 4-for-5 with three RBIs and scored four times to back Jesse Litsch's strong outing. Litsch (9-7) pitched six sharp innings to win for the first time since June 26.

YANKEES 5, ORIOLES 3: At Baltimore, Carl Pavano (1-0) — pitching in the major leagues for the first time since April 2007 — allowed three runs and seven hits in five innings for New York. It was Pavano's 20th start with the Yankees since signing a four-year, $39.95 million contract before the 2005 season. Mariano Rivera got three outs for his 30th save in 31 tries. Jason Giambi hit his 25th homer and drove in three runs, and Hideki Matsui had a solo shot for his 500th career RBI.

TIGERS 4, ROYALS 0: At Kansas City, Mo., Zach Miner pitched three-hit ball for seven innings, Miguel Cabrera hit his third homer in two games to reach 100 RBIs and Detroit handed the Royals their seventh straight loss.

ANGELS 7, TWINS 5: At Anaheim, Calif., Mark Teixeira went 3-for-3 with a home run and Francisco Rodriguez closed out another strong bullpen performance, helping the Angels end Minnesota's four-game winning streak. Rodriguez earned his major league-leading 49th save. Teixeira and Vladimir Guerrero each drove in two runs for the Angels in the matchup of AL division leaders.

ATHLETICS 5, MARINERS 1: At Seattle, Dana Eveland made a smooth return to the majors, pitching shutout ball into the seventh inning for Oakland. Eveland (8-8) had been sent down to Triple-A Sacramento earlier this month after going 0-3 with a 10.59 ERA in a four-start span.

INDIANS 8, RANGERS 7: At Arlington, Texas, pinch-hitter Jamey Carroll singled home the go-ahead run in the eighth inning and Cleveland rallied from a six-run deficit to win its sixth straight game. Kelly Shoppach hit a three-run homer and later got an infield single that set up the Indians' tiebreaking run.