Randy Wells pitched six strong innings and Marlon Byrd drove in two runs as the Cubs beat the Pittsburgh Pirates 6-3 Sunday to avoid a three-game sweep.Wells was impressive again after pitching his first career shutout in Monday’s 7-0 win over the Giants. He pitched a two-hitter to outduel Tim Lincecum in his first-career complete game. Wells (7-4) allowed one run while scattering seven hits. He struck out two and walked two. He is 6-1 over his last eight outings after going 0-3 with a 7.38 ERA in his first nine starts once returning from the disabled list. In the last month, Well is pitching more like his 2009 season, when he led all rookies with a 3.05 ERA. Sean Marshall pitched a scoreless ninth for his fourth save in eight chances. Cubs closer Carlos Marmol had the day off after blowing Saturday’s save and throwing 39 pitches.The Cubs won just for the third time in 10 games. Pirates starter Charlie Morton (9-9) allowed four runs, three earned on seven hits. He struck out two and walked five and was done in by two errors by shortstop Ronny Cedeno.Neil Walker hit a two-run shot in the eighth and Derrek Lee had three hits for the Pirates, who have lost six of eight. The Cubs had runners on first and second with no outs in the first three innings, but failed to score until the third thanks to Cedeno’s error. Trailing 1-0, Carlos Pena hit a sharp grounder to Walker at second base. Walker made a low throw to Cedeno, who was covering second to get one out, but Cedeno’s throw to Lee at first was wide, allowing Tony Campana to score from second on the overthrow.With two outs in the fourth inning and Koyie Hill on second, Starlin Castro hit a grounder to third baseman Josh Harrison. Harrison fielded the grounder, but his throw to first took Lee off the base so Lee attempted to tag Castro. First baseman umpire Jim Wolf ruled Lee’s tag did not make contact with Castro. Hill, who never stopped on the base paths ended up scoring from second on the play. Lee argued with Wolf and Pirates manager Clint Hurdle came out of the dugout to also have an animated discussion with Wolf to no avail. The Cubs added to its lead in the fifth. With runners on first and second and no outs, LaHair hit a ball that brushed Morton’s jersey. Cedeno fielded the grounder but the ball rolled out of his mitt, allowing LaHair to reach safely on the error.With the bases loaded, Byrd hit a sacrifice fly. Hurdle pulled Morton after he hit Darwin Barney with a pitch to load the bases again. Pirates reliever Tony Watson got Hill to hit a bouncer back to him, but the ball pulled him off the mound forcing him to go to first to get the out, which allowed Pena to score and make it 4-1. LaHair hit a two-out, RBI bloop single off Watson in the sixth inning to make it 5-1. LaHair finished with two hits in his season debut. After hitting a go-ahead grand slam in the ninth during Saturday’s win, Lee hit an opposite field RBI single in the first inning to give the Pirates a 1-0 lead. Since joining the Pirates, all nine of Lee’s RBI have come against the Cubs.Lee is 6 for 9 with a grand slam since returning from the disabled list Saturday. Walker hit a two-run homer off Cubs reliever Jeff Samardzija in the eighth inning. It was Walker’s 12 of the season. Byrd added an insurance run in the eighth for the Cubs with an RBI single off Pirates reliever Jose Veras.

NOTEAS—Matt Garza is Monday’s scheduled starter against the Reds. He is 0-2 with 5.06 ERA in three career starts against the Reds. … Pena had a career-high four walks. Pena has reached base 10 consecutive times.