CHICAGO(AP) Ryan Doumit and the Pittsburgh Pirates had a quite a day at Wrigley Field.

Doumit collected four hits and four RBIs to help the Pirates beat the Chicago Cubs 8-2 Wednesday night for a doubleheader sweep.

''Hey, that's baseball,'' Doumit said. ''To have a day like this, I can't remember the last time we won at Wrigley, let alone two games in one day.''

The Pirates had won only once in Chicago this season, on May 25. Their last doubleheader sweep at the Cubs' cozy ballpark was June 20, 1983, before many of the current Pirates were born.

Jeff Karstens tossed five innings for the second victory by a no-name Pittsburgh pitcher over a high-priced Cubs starter on the day. A few hours before Karstens beat Carlos Zambrano , Charlie Morton threw a four-hitter in a 4-0 victory over Ted Lilly .

While Karstens and Morton make just over $400,000 each, the combined 2009 salary of Zambrano and Lilly is $31.75 million - or about $577,000 per start.

Doumit went 4 for 4 with his 10th homer in the second game. Jason Jaramillo , who backs up Doumit at catcher, had a two-run double in the opener.

''To sweep a doubleheader is tough anywhere, home or road,'' Pirates manager John Russell said. ''To come in here and beat two really good pitchers ... I'm really proud of the way the guys battled.''

Zambrano (9-7) gave up four runs and six hits with four walks over six innings in his final outing of a frustrating season. The right-hander failed to post double-digit victories for the first time in his seven years as a full-time starter.

The leader of a rotation that had carried the Cubs to the 2007 and 2008 NL Central titles, Zambrano recently said he would retire if he has a similar season next year - even though he still would have two years left on his $91.5 million contract.

''Look, everybody expects more out of him,'' Cubs manager Lou Piniella said. ''Let's chalk this up as a season where he wasn't at his best. He's talked about working hard and having a big season next year.''

Karstens (4-5), who has pitched mostly in relief this season, allowed two runs and five hits. Morton (5-9) was dominant in the opener, shutting down the same Chicago team that lit him up for 10 runs seven weeks earlier.

''I try not to put so much emphasis on one game,'' Morton said of the 17-2 loss on Aug. 14. ''But it's a big step in the sense that, yeah, I came here and gave up 10 runs in an inning. This time ... I was throwing pretty much everything for strikes. Just being more aggressive with my pitches.''

The 25-year-old right-hander, acquired in the June 3 trade that sent Nate McLouth to Atlanta, had a career-high eight strikeouts, walked three and hit two batters. Morton had never thrown more than seven innings in a game.

''You take away the (Aug. 14) start,'' Russell said, ''and his numbers have been pretty good.''

Morton had a 3.66 ERA in his other 17 starts.

Lilly (12-9) allowed five hits in seven innings and retired 19 of the last 21 batters he faced but still suffered his second home loss this season. The Cubs' lone All-Star finished with a team-best 3.10 ERA but recorded his fewest victories since 2005, when he had 10 for Toronto.

''One (reason) I was brought here was to try to get this team to the postseason and win some postseason games,'' said Lilly, who in 2007 lost his only playoff start with the team. ''I don't really feel I've met expectations at this point. Maybe next year will be different.''

Lilly walked two of the game's first three batters before Lastings Milledge singled to load the bases. Steve Pearce then grounded to second baseman Andres Blanco , who shoveled to shortstop Ryan Theriot for the second out.

Milledge slid hard and kicked his legs sideways, knocking down Theriot as a run scored. Milledge was able to reach the bag with his arms, so he wasn't called for leaving the baseline, but fans still booed him the rest of the day.

''A clean play,'' Theriot said. ''Take guys out ... that's how you play the game. I'd do the same thing.''

Jaramillo followed with his double to make it 3-0 and Brian Bixler singled home a run on the next pitch.

Pittsburgh struck first again in the nightcap, with Andrew McCutchen hitting a leadoff triple and scoring on Milledge's single. The Pirates added three more in the third on Doumit's two-run double and Brandon Moss ' single. Doumit's RBI single in the seventh helped break open the game, and he went deep in the ninth.

NOTES: Before Wednesday, the Pirates had been 3-15 at Wrigley since Sept. 21, 2007. ... Zambrano went 2-5 with a 5.03 ERA in 13 home starts. He was 7-2 with a 2.73 ERA on the road. ... The Cubs went over the 3 million attendance mark for the sixth straight season. ... Pittsburgh pitchers have allowed only one home run in the last 10 games. ... Zach Duke has the Pirates' only other shutout this year. ... Cubs 1B Derrek Lee , who fouled a ball off his foot Tuesday, sat out the first game. After X-rays showed no damage, he played in the second.