The Pirates will try for their first six-game win streak in four seasons Monday night when they open a three-game set against the Cubs, who have not scored in their last 25 innings.Pittsburgh (54-40) owns baseball's best home mark at 32-14, but was only 11-10 when Chicago (38-56) visited back in May for the lone previous 2012 series between these teams. The Pirates averaged 2.5 runs while hitting .210 over their first 21 home games.It's been a different story since Pittsburgh's May 25-27 three-game sweep of Chicago kick-started this 21-4 stretch at PNC Park in which the Pirates are batting .271 and averaging 4.8 runs."We love it, we're battling and playing hard for the city of Pittsburgh," pitcher Jeff Karstens said.Pittsburgh leads the NL wild-card race and trails Central leader Cincinnati by one-half game. The Pirates are seeking their first six-game win streak since a seven-game run May 6-12, 2008.MVP candidate Andrew McCutchen was already performing well at home before the Cubs' previous visit, with a .352 average at PNC Park at the time. He is hitting .419 in his last 25 games in Pittsburgh to raise his home average to .390 -- the best in the majors.McCutchen, who continues to lead baseball with a .372 average overall, went 4 for 10 with three walks in the first series between these clubs. Pedro Alvarez homered and led the Pirates with five RBIs in that set.Alvarez is surging with four homers, seven RBIs and six runs scored in his last six games. He had a two-run homer in Sunday's 3-0 victory over Miami that completed a weekend sweep.Chicago had won 14 of 19 before being outscored 23-1 while being swept over the weekend in St. Louis. The Cubs have not scored since Darwin Barney's sacrifice fly in the second inning of Friday's 4-1 defeat.It might not be easy to get untracked against Erik Bedard (5-10, 4.55 ERA). Chicago is 10-18 against left-handed starters, and failed to score while managing two hits and four walks over six innings against him May 27 in a 10-4 loss.Bedard gave up two runs over 6 2/3 innings Tuesday to earn a 6-2 victory at Colorado. He had been 0-4 with a 7.99 ERA over his previous five outings."I felt the same as I've felt in my other games," Bedard said. "I just threw more strikes."He owns a 2.95 ERA at home compared to a 5.90 mark on the road.Cubs starter Jeff Samardzija (6-8, 4.57) has a 1.29 ERA in 11 career relief appearances against the Pirates heading into his first career start against them.The right-hander has pitched well in three July outings, going 1-1 with a 2.37 ERA. He yielded one run over five innings Wednesday in a 5-1 home victory over the Marlins.Pittsburgh has never had a winning record within NL Central play. The Pirates are 21-13 against their division rivals as they open a stretch of 13 straight against them.