CHICAGO -- When the Chicago Cubs' starting pitching is on target, the rest of Joe Maddon's team tends to follow suit.

And after a disappointing first half when the defending World Series champions were mired in mediocrity, things have turned dramatically ever since as the Cubs' starters have picked up steam.

Wednesday night provided the latest chapter.

Jake Arrieta allowed only two hits in 6 2/3 innings and Anthony Rizzo drilled a three-run double and drove in four runs as the Cubs beat the crosstown rival White Sox 8-3 at Guaranteed Rate Field.

Rizzo's bases-loaded double sparked a four-run fifth inning before the Cubs -- 10-2 since the All-Star break -- added another run in the sixth. The win, coupled with the Milwaukee Brewers' loss to the Washington Nationals, moved the Cubs into first place in the National League Central by one-half game.

Arrieta's effort was a big reason why.

"Starting pitching -- we feed off of it," said Rizzo, who was 3-for-4.

The White Sox have lost 14 of their last 16 games.

Rizzo added an RBI single in the eighth inning and Addison Russell homered in the ninth to cap the Cubs' scoring. Alen Hanson homered in the White Sox eighth off reliever Mike Montgomery.

The Cubs' offensive burst was more than enough for Arrieta (10-7), who surrendered a double in the fifth inning to Omar Narvaez and Yoan Moncada's first major league home run with two outs in the seventh inning.

Arrieta struck out five and walked two as he won for the third time in his last five outings (3-1).

"I still feel like I haven't pitched my best yet -- and that's a good feeling," Arrieta said. "With what I have right now, the command I display and the secondary pitches that I'm capable of utilizing, I have a lot of weapons and I feel good."

With Arrieta rolling, the Cubs' offense did, too.

Rizzo's three-run double in the fifth inning gave the Cubs a 4-0 lead. Victor Caratini led off with a single before Jason Heyward walked and Kris Bryant reached on an error. Rizzo cleared the bases with a double that soared over the head of center fielder Adam Engel.

That chased White Sox starter James Shields (2-3), who didn't allow a hit until the fourth inning but left after giving up five runs (three earned) while walking three and striking out four in four-plus innings.

Shields, who has struggled this season with giving up home runs, didn't allow one Wednesday, but couldn't keep going after his strong start.

"That's kind of where he's been a little bit over the last few starts," White Sox manager Rick Renteria said. "He's still trying to make adjustments, he's trying to go out there and compete, he's trying to do all he can and there's only so much he can do in the end.

"Today was one of those days where we just have to keep fighting."

The Cubs extended their lead to 5-0 with two outs on Jon Jay's RBI single.

Hanson got the White Sox on the board with a sacrifice fly that scored Moncada, who walked with one out before advancing to third on Narvaez's double.

After neither team managed a hit in the first three innings, the Cubs broke through in the fourth.

Rizzo singled with one out after Shields, who issued a second-inning walk, retired 10 of the first 11 batters he faced. After Rizzo advanced to third on a Ben Zobrist single, he gave the Cubs a 1-0 led on Kyle Schwarber's RBI single.

With everything seemingly rolling in the right direction and the Cubs back atop the division standings, it's just a matter of keeping things rolling, manager Joe Maddon said.

"We have to be more efficient (offensively) as we move along and keep working those at-bats," Maddon said. "It's always nice to wake up (in first place)."

NOTES: Cubs LHP Brett Anderson was designated for assignment after being activated from the 60-day disabled list. Anderson was 2-2 with an 8.18 ERA for the Cubs this season. Anderson had been sidelined with a lower back strain. ... White Sox OF Avisail Garcia will be sidelined for "a couple of weeks," general manager Rick Hahn said after an MRI showed a ligament strain in Garcia's right thumb. Garcia also has experienced discomfort in his right middle finger recently. Hahn said Garcia likely won't require a procedure on the thumb before he returns. ... The White Sox traded RHP Anthony Swarzak to the Milwaukee Brewers for OF Ryan Cordell, the Brewers' 17th-rated prospect, according to MLB.com. ...RHP Jake Petricka was reinstated from the 10-day disabled list after being placed on the DL June 29 with a right elbow strain. He will take Swarzak's roster spot.