By Bruce Levine–

CHICAGO (CBS) — After a humbling first half of the season in which they found themselves 5.5 games behind the Brewers at the All-Star break, the Cubs have looked much more like their 2016 championship club the last two weeks.

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Chicago has surged at the start of the second half by winning 11 of their first 13 games and turned that NL Central deficit into a 1.5-game lead as it starts a three-game series at Milwaukee on Friday.

As the Cubs (54-47) have found their great form, the Brewers (54-50) have gone 2-11 and now trails their neighbors to the south by three games in the loss column. Chicago’s improved play has been spearheaded by its pitching rotation, as the starters are 10-0 with a 2.50 since the All-Star break. On Thursday evening, left-hander Jon Lester continued that trend, throwing seven innings of two-run ball in the Cubs’ 6-3 win against the White Sox at Guaranteed Rate Field.

“You guys call it in-house competition,” Lester said. “I like to call it the chain theory. Nobody wants to be the weak link. I don’t like in-team competition. When you use that term as a pitcher, it seems like you might be rooting against guys. I like to think of it that we have a chain going. We are playing well in all aspects of the game.”

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On top of the starting pitching, the Cubs are also getting more production out of Kyle Schwarber, who hit two home runs Thursday.

“Obviously, this whole series was momentum for everyone in the room,” Schwarber said.”I am going to stay even-keeled, and I know my teammates will stay even-keeled going into the Milwaukee series. We just want to go out and play our brand of baseball.”

Earlier Thursday, manager Joe Maddon cautioned his team not to get overconfident. The Cubs have indicated that’s not the case, but they know the good vibes are rolling as an important divisional series awaits.

“Obviously we are all human and know what is going on,” Lester said. “At the same time, we cannot look at it as that. We have to look at this as one game tomorrow. We will show up Friday at 7 p.m. and try and beat the Brewers. We did that tonight with the White Sox. When Saturday comes, we will deal with trying to win that game.”

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Bruce Levine covers the Cubs and White Sox for 670 The Score and Follow him on Twitter @MLBBruceLevine.