The Cubs look for their sixth consecutive victory as they try to continue their dominance of the Pirates as the division rivals open a three-game series Friday at Wrigley Field.Chicago (65-44) further distanced itself from one of the teams chasing it within the Central by completing a four-game sweep at Milwaukee with an 11-4 victory on Thursday. The teams were tied atop the division just six days ago, but are now separated by five games."There's baseball to be played in August, September," Cubs manager Lou Piniella said. "But certainly, coming in here and beating a good opponent at their home ballpark four times is something to feel good about."Jim Edmonds homered twice Thursday -- including a grand slam -- to help the Cubs improve to 27-19 versus NL Central foes. That includes a 9-3 mark versus the last-place Pirates (50-58).Chicago took five of six from Pittsburgh at Wrigley Field earlier this year, and looks to open its nine-game homestand successfully. But while the club is an NL-best 39-14 at home, it is only 7-6 there since its franchise record-tying 14-game winning streak (May 18-June 22).The Cubs have had better results when right-hander Jason Marquis (6-6, 4.69 ERA) takes the mound at home. They have won seven of his 10 starts at Wrigley, though he is 3-3 with a 5.81 ERA in those appearances.In his most recent outing there, Marquis yielded six runs and nine hits in six innings, but finished without a decision as Chicago eventually beat Florida 9-6 on Sunday."I got behind early and didn't like the direction the game was headed, but we hung in there and the offense came alive and settled down," Marquis told the Cubs' official Web site.Marquis is 7-5 with a 4.03 ERA in 21 career games against the Pirates, but 2-0 with a 3.12 ERA in three matchups this season.The Pirates, who are 14 1/2 games back of the Cubs, capped a 3-4 homestand with a 7-4 loss to Colorado on Wednesday.While they are well out of contention in the NL Central, they have started making several moves to begin rebuilding for the future. After sending Xavier Nady and Damaso Marte to the New York Yankees on Saturday, they dealt outfielder Jason Bay to Boston on Thursday as part of a three-team trade that moved Red Sox outfielder Manny Ramirez to the Los Angeles Dodgers.In exchange for Bay, Pittsburgh acquired reliever Craig Hansen and outfielder Brandon Moss from Boston and third baseman Andy LaRoche and pitcher Bryan Morris from the Dodgers.Right-hander Jeff Karstens came to Pittsburgh in the deal for Nady and Marte and makes his Pirates debut against a Cubs' team that has hit .295 with 14 homers versus Pittsburgh pitching this season.The right-hander, filling the rotation spot left open after John Van Benschoten was demoted to Triple-A Indianapolis on Sunday, went 6-4 with a 3.80 ERA in 12 starts at Triple-A Scranton/Wilkes-Barre in the Yankees' system."I don't expect him to go out and throw eight shutout innings," manager John Russell told the Pirates' official Web site. "I'm just looking for the actions in his pitches, how he competes (and) mound presence."Karstens compiled a 3-5 mark with a 5.65 ERA in 15 games -- nine starts -- for the Yankees from 2006-07, but he has never faced an NL club.