SAN DIEGO - Yasmani Grandal's three-run homer capped a five-run fourth inning, and the San Diego Padres beat the Arizona Diamondbacks 6-4 on Saturday night to stretch their winning streak to five and reach the .500 mark for the first time in two years.
Jason Marquis (9-2) allowed three runs and three hits in 6 2/3 innings to win his eighth straight decision. San Diego (34-34) pulled to within three games of first-place Arizona in the NL West.
The last time the Padres were at .500 was April 10, 2011, when they were 4-4.
Huston Street, who returned from the disabled list Friday, earned his 12th save in 13 opportunities. He gave up an RBI double in the ninth to Gerardo Parra before getting Didi Gregorius to fly out to center for the final out.
Arizona's Wade Miley (4-6) had been staked to a 3-0 lead in the first inning, in part on a two-run homer by catcher Miguel Montero.
Miley faced the minimum over the first three innings and had allowed only a walk to Grandal when Everth Cabrera led off the fourth with a single to right. Chris Denorfia followed with a hard shot to shortstop that Gregorius misplayed for an error.
Chase Headley drove in San Diego's first run with a single to center. After Kyle Blanks reached on a fielder's choice, Logan Forsythe hit a sacrifice fly to score Denorfia. Jesus Guzman followed with a single to right, and Grandal, who served a 50-game suspension for testing positive for elevated levels of testosterone, hit his first homer of the year - a 442-foot shot into the left-field bleachers.
That gave the Padres a 5-3 lead on five unearned runs. Kyle Blanks added his seventh home run in the sixth off Miley to extend San Diego's advantage.
The Diamondbacks had scored their third run in the fourth when Cliff Pennington's fielder's choice with the bases loaded scored Cody Ross.
Arizona threatened in the eighth on singles by Gregorius and Montero, but Dale Thayer struck out Cody Ross and Jason Kubel looking to end the inning.
Padres outfielder Carlos Quentin missed the game because of an injured left shoulder, which he said he hurt taking a swing Friday.