CHICAGO (AP) — Javier Baez homered and the Chicago Cubs took advantage of huge mistake by Ryan LaMarre, beating the crosstown White Sox 8-3 on Saturday night to increase their lead in the NL Central.

Ben Zobrist added two hits and two RBIs as the Cubs moved 21⁄2 games ahead of second-place Milwaukee. Coupled with the Brewers’ 3-0 loss at Pittsburgh, the Cubs lowered their magic number for clinching their third straight division title to six.

Jon Lester (17-6) labored through five innings to move into a tie with Washington ace Max Scherzer for the NL lead in wins. The left-hander allowed three runs, two earned, and eight hits in his second straight victory.

With the Cubs in need of a win to help hold off the hard-charging Brewers, Baez delivered once again.

He hit a screaming liner for a two-run homer in the first and a run-scoring single in a three-run ninth. He has 34 homers and an NL-best 110 RBIs.

Tim Anderson connected for the White Sox, who lost for the fourth time in six games. Lucas Giolito (10-12) was charged with five runs and seven hits in 6 2/3 innings at Guaranteed Rate Field.

Anderson’s leadoff drive in the third tied it at 2 and made him the first shortstop in franchise history with at least 20 homers and 20 steals in a single season. But LaMarre’s defensive miscue in the fifth helped the Cubs grab control.

With one out and runners on first and second, Daniel Murphy hit a drive to left field. LaMarre broke in on the ball and it sailed over his head for an RBI double. Zobrist followed with a bouncer up the middle for a two-run single, giving the Cubs a 5-2 lead.

The White Sox got one back on Matt Davidson’s RBI single in the bottom half of the inning. But Carl Edwards Jr., Jesse Chavez, Justin Wilson and Steve Cishek closed it out for the Cubs, combining for four innings of hitless relief after Lester departed.