PHOENIX -- The Los Angeles Dodgers took advantage of two unearned runs and rode Kenta Maeda's pitching to a 3-2 victory over the Arizona Diamondbacks on Friday night.

Maeda (15-9) wobbled at times, walking three, including back-to-back free passes in the second but got stronger as the game went on. In five innings, he allowed one run, three hits and struck out six.

The Dodgers maintained their four-game lead in the National League West over San Francisco, which defeated St. Louis 8-2 on Friday.

Reliever J.P. Howell gave up a double by Jake Lamb to start the sixth. Josh Fields replaced Howell and walked Welington Castillo. But Fields struck out Yasmany Tomas and Brandon Drury and got a fly ball from Mitch Haniger to end the threat.

Pedro Baez pitched a scoreless seventh for the Dodgers. Grant Dayton and Joe Blanton combined to blank the D-backs in the eighth. Blanton walked three batters, but escaped when he got Rickie Weeks to ground into a force play.

In the ninth, Kenley Jansen gave up a triple to Chris Owings. Owings scored on a sacrifice fly by Paul Goldschmidt, but Jansen got Lamb to ground out to earn his 45th save.

Zach Greinke (12-7) took the loss for the Diamondbacks, allowing three runs (one earned) and four hits in six innings.

Arizona's Jean Segura singled and doubled, and needs 16 hits in the final 15 games to reach 200.

Chase Utley had two of the Dodgers' five hits.

The crowd hadn't fully settled into their seats before the Dodgers picked up two runs.

Utley led off the game with a double down the right field line. He advanced to third on Greinke's wild pitch and scored on Justin Turner's triple to right. Turner scored on a passed ball by Welington Castillo.

Maeda lost track of the strike zone in the second inning, walking two. He limited the damage to one run when a check-swing grounder by Haniger drove home Castillo, who had singled.

The Dodgers put two runners on base in the fourth when Adrian Gonzalez singled and Josh Reddick walked. Howie Kendrick hit a grounder to short, where Owings retired Reddick on a force play, but second baseman Segura threw the ball away attempting an inning-ending double play. Gonzalez scored, giving the Dodgers their second unearned run and a 3-1 lead.

NOTES: Brock Stewart (1-2, 6.55 ERA) will replace Bud Norris (6-10, 5.05) as the Dodgers' starting pitcher Saturday night against the Diamondbacks, manager Dave Martinez announced before Friday night's game. Stewart has thrown well in his past two starts. "Brock has earned the opportunity for another start," Martinez said. Stewart and Norris could be in the picture as long relievers in the postseason. The Dodgers' top three postseason starters are expected to be Clayton Kershaw, Rich Hill and Kenta Maeda. ... The Dodgers are 4-4 on their season-long 10-game road trip. ... The Diamondbacks had their four-game home winning streak snapped, their longest since July 2014. They are 12-9 at Chase Field since Aug. 5. ... 2B Jean Segura has 184 hits as he bids to become the second player in franchise history to reach 200 (Luis Gonzalez, 206 in 1999).