SAN FRANCISCO -- Jake Arrieta wasn't at his best Monday night. However, whenever he is pitching in California, everything seems to come out all right.
Javier Baez hit an inside-the-park home run to stake his starter to an early lead, and Arrieta continued his pitching prowess in the Golden State as the Chicago Cubs beat the San Francisco Giants 5-3.
Arrieta (11-8) scattered nine hits over 6 1/3 innings and allowed three runs (two earned).
"Physically, I didn't really feel on my game," he said. "I noticed it from the start, when I started to play catch to the pregame side. What I really wanted to do was be efficient and not put guys on for free."
First-place Chicago (59-52) increased its lead over second-place Milwaukee to 1 1/2 games in the National League Central while snapping San Francisco's modest two-game winning streak.
"I'm a scoreboard watcher. Guilty," Cubs manager Joe Maddon said. "But if you take care of your own business, you'll be OK."
Chicago closer Wade Davis remained perfect in save situations by earning his 24th of the season with a scoreless ninth. That after Pedro Strop and Brian Duensing combined for 1 2/3 innings of scoreless, hitless relief.
"I thought Jake was really good," Maddon said. "Give Duensing and Strop credit, they were outstanding again tonight. They settled that thing down when it needed to be settled down. I'll take it."
In leading the Cubs to their 16th win in 23 games since the All-Star break, Arrieta improved to 7-1 with a 1.14 ERA in his past nine regular-season starts in California dating back to Aug. 25, 2015.
Arrieta struck out five and didn't walk anyone as the Giants lost at home to Chicago for only the third time in nine games.
"When you have a lead, that's exactly what you want to do -- pitch to contact, work the corners and try to keep guys off balance, and I was able to do that really well," Arrieta said.
Staked to a 5-0 lead, Arrieta surrendered his first two runs in the sixth inning on rookie Ryder Jones' first career home run, into the right-center-field bleachers. Pablo Sandoval, who doubled earlier in the inning, scored on Jones' homer.
"Those guys did some good things," Giants manager Bruce Bochy said of his hitters. "We had some good at-bats in that game. It comes down to you have to get hits with runners on base."
The Cubs scored twice on the team's first inside-the-park home run in over a year. Baez hit a ball of the right-center-field fence that bounced back toward right after Carlos Moncrief misplayed the drive. Moncrief was playing right field in just his sixth game with the Giants.
With Heyward leading the way after his two-out single, Baez steamed around the bases and slid across the plate head-first to barely beat a tag from catcher Buster Posey, who had to wait for Moncrief's strong throw, which raised an eyebrow from Maddon.
"That guy, that might be the best arm I've seen," Maddon said. "That's a Bo Jackson arm. That was Bo good. That was a big hit at the time."
Moncrief smiled when he heard Maddon's remark, but he had a different take on the play.
"I was trying to go as hard as I can to keep that run from scoring," Moncrief said. "It wasn't like I'm trying to make the best throw of my life. I was just trying to keep the guy from scoring.
"Today we worked on everything, angles coming off the right field wall. That was like the only one like that,. I wasn't really anticipating it would bounce like that. Now I know for next time, though I hope there's not a next time."
Anthony Rizzo was the previous Cub to hit an inside-the-park homer on June 29, 2016, at Cincinnati.
Jay, who led off the fifth with a single, scored from second on Rizzo's single off Giants starter Matt Moore to make it 4-0. Rizzo scored later in the inning when Albert Almora Jr. singled to left-center.
Moore (3-12) gave up five runs on eight hits and a walk in six innings. He struck out seven.
NOTES: Monday marked the 10-year anniversary of Barry Bonds hitting his 756th home run to break Hank Aaron's major league record. ... The Cubs opened a trip Monday night that represents the final six games they are scheduled to play west of St. Louis this season. Chicago's final 46 games are against clubs in the East and the Midwest. ... Giants rookie Carlos Moncrief started in right field as a healthy Hunter Pence got a rest. ... Cubs C Willson Contreras was honored as NL Player of the Week after batting .455 (10-for-22) with a five home runs and 13 RBIs in six games.