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SAN DIEGO -- Joel Pineiro and the St. Louis Cardinals can do little wrong these days.

Pineiro won his sixth straight decision with another strong outing and the Cardinals padded their NL Central lead with a 5-1 victory over the San Diego Padres on Thursday night.

Brendan Ryan hit a grand slam in the second inning to stake Pineiro (12-9) to a 4-0 lead and the right-hander made it stick.

The Cardinals' victory increased their lead to a season-high seven games over the Chicago Cubs, who lost 7-2 at the Los Angeles Dodgers. St. Louis won for the 16th time in 21 games.

"We're playing well, just keep pushing," St. Louis manager Tony La Russa said.

Pineiro has played a large part in the Cardinals' bid to run away with the division race. He has not lost since late June and St. Louis has won his last nine starts.

"When he has that sinker working, I can really kind of shade the hitter and it makes for routine ground balls," said Ryan, who hit his first career grand slam.

Pineiro had control issues in the first two innings before he settled down and held the Padres to one run and four hits over 7 2/3 innings. He gave credit to Ryan's second home run of the season for helping him to relax.

"The big grand slam by Ryno kind of gave me a little bit of extra breathing room to settle down and go out there and work," Pineiro said.

Pineiro also received steady play from his defense, including catcher Yadier Molina, who threw out two runners attempting to steal. San Diego had leadoff walks in the first and third innings erased when Molina threw out would-be base stealers.

"That's huge, he's the best," Pineiro said. "If you give him a little time to throw the ball he's going to most of the time get the guys out. He's the best behind the plate."

Molina has thrown out 14 of 42 (33.3 percent) of potential base stealers this season.

"It takes you out of a lot of jams and saves it from being a bigger inning," Pineiro said.

The Cardinals have beaten San Diego nine straight times, including a three-game sweep last weekend in St. Louis.

Pineiro struck out six, walked two and combined with three relievers on a four-hitter.

The only run Pineiro allowed was a homer to rookie Kyle Blanks, who connected in the second inning for his ninth homer. Blanks homered for the third time in four games.

"[Pineiro] had good action down in the zone," Padres manager Bud Black said. "We just couldn't solve him."

Ryan's first career grand slam came off Tim Stauffer (1-6) after the righty hit Matt Holliday leading off the inning. With one out, Stauffer walked Mark DeRosa and hit Molina to load the bases. Ryan hit a 3-1 pitch into the left field stands for the Cardinals' seventh grand slam this season.

"I had the green light at 3-0 but didn't like the pitch," Ryan said. "The next one was up and I put my best swing on it."

Said Stauffer: "I threw the [fastball] that rode back over the middle and he put a good swing on it."

Stauffer gave up four runs and four hits over five innings. He struck out six and walked two.

St. Louis added a run in the sixth on Holliday's leadoff triple off Greg Burke and Molina's groundout.

The Padres were held to one run for the second straight game as they lost for the sixth time in eight games.

Khalil Greene struck out pinch-hitting in the ninth in his first appearance in San Diego, where he played his first six seasons before he was traded to St. Louis in the offseason.

Game notes

Pineiro has allowed six home runs this season, one in each of his last three starts. ... RHP John Smoltz, who signed a deal with St. Louis on Wednesday, was in uniform Thursday and is Sunday's scheduled starter in the finale of the four-game series. ... DeRosa walked three times to tie his career high for the third time. ... Padres rookie Everth Cabrera was thrown out trying to steal second base in the third inning, just the third time he's been caught. Cabrera, who has 18 stolen bases, leads the NL in stolen base percentage.