SAN DIEGO -- For a pitcher who didn't start his season until last Monday, Charlie Morton is rapidly making up for lost time.

The Pittsburgh right-hander not only held San Diego to two runs and three hits in seven innings Saturday night at Petco Park, but he drove in the decisive run with an infield grounder in the sixth inning as the Pirates defeated the Padres 5-2.

It was the eighth win in nine games for the Pirates, who saw their seven-game winning streak end Friday night on catcher Derek Norris' walk-off grand slam in the ninth inning.

Morton was making only his second start since returning from right hip surgery performed in September. He walked one and struck out two and needed only 85 pitches to navigate seven innings. One of the two runs he allowed was unearned on a throwing error by first baseman Pedro Alvarez.

Since coming off the disabled list, Morton has allowed four runs (three earned), 11 hits and a walk in 14 innings for a 1.93 earned run average.

"I wanted to make a contribution after missing the first month of the season," Morton said. "I was really aggressive. My sinker was working and I was throwing curves for strikes. I'm just trying to every pitch count."

Morton retired the Padres in order in five of the seven innings he worked and set down the last 11 Padres he faced. He issued one walk and struck out two. Sixteen of his 21 outs came on ground balls.

"We couldn't solve his sinker and curveball combination," Padres manager Bud Black said of Morton.

And the Pirates bullpen didn't let up. Left-handed reliever Tony Watson struck out the side in the eighth. Right-handed closer Mark Melancon allowed the fourth Padres hit of the game in the ninth before completing his 13th save.

The Pirates' winning rally began with Alvarez's one-out double to center in the sixth. Padres starter Tyson Ross then hit catcher Francisco Cervelli with a pitch and shortstop Jody Mercer reached on an infield single to load the bases.

Morton hit a chopper that second baseman Cory Spangenberg charged and fielded on the infield grass, leaving him with only a play at first on Morton.

The Pirates added two insurance runs in the ninth against Padres right-handed reliever Kevin Quackenbush.

Pittsburgh third baseman Josh Harrison and right fielder Gregor Polanco hit back-to-back, one-out singles. Center fielder Andrew McCutchen doubled home Harrison and Polanco scored on left fielder Starling Marte’s groundout to first.

Ross (2-5) allowed three runs (two earned), seven hits and two walks with two strikeouts in six innings to take the loss -- settling down after a shaky first two innings.

Eight of the first 12 batters that Ross faced reached base and Pittsburgh loaded the bases in both innings. But they also scored only one run in each inning despite getting five hits and two walks.

The Pirates' first run was unearned. McCutchen started the rally with a two-out single. But the key play came on Marte’s ensuing grounder to third. Padres third baseman Will Middlebrooks fielded the ball but threw a one-hopper that first baseman Yangervis Solarte couldn't handle – the error charged to Middlebrooks.

Second baseman Neil Walker followed with a run-scoring single.

The Padres immediately tied the score. Center fielder Will Venable drew a game-opening walk -- the only allowed by Morton -- and raced home on Solarte's line drive double up the gap in left center. However, the Padres were not able to advance Solarte from second.

The Pirates regained the lead in the second, although they scored only one run on three hits, a walk and three stolen bases.

Mercer singled to open the inning, stole second and scored on Harrison's one-out single. After Harrison stole second, Polanco reached on an infield single -- a diving stop by shortstop Alexi Amarista kept the ball from rol