When San Diego's Nick Hundley came to the plate in the eighth inning, he did a double take.

The Padres catcher thought his eyes were betraying him when he spotted New York starter Mike Pelfrey coming in from the bullpen during San Diego's 6-1 win over the slumping Mets on Tuesday night.

Hundley had three hits, including two triples with the final one off Pelfrey, to lead a 15-hit San Diego attack.

"It was weird seeing him come out of the pen," Hundley said. "It was like, 'Who is this guy?' To take a swing like that off an ace like that gives me a lot of confidence."

Pelfrey, who is scheduled to start Friday against Milwaukee, came in with the Mets down 5-1. The right-hander left his last start on Saturday at Arizona after four innings when he was hit by a line drive on the right elbow. Since X-rays were negative and Pelfrey only threw 50 pitches, manager Terry Collins wanted to get him some work.

"It felt good to get back on the mound," said Pelfrey, who only faced three batters, threw eight pitches and allowed a one-out RBI single by Alberto Gonzalez before he was replaced.

"We wanted to get him in the game, get him an inning's work and really keep his workload down so he could have a little bullpen with some game action," Collins said.

Pelfrey, who has 138 career starts, made just his fourth career appearance out of the bullpen. It was his first bullpen duty since April 17, 2010 when he worked a scoreless 20th inning to earn his only career save in a 2-1 win at St. Louis.

Rookie Cory Luebke (5-6) pitched six strong innings for San Diego. Luebke allowed one run and three hits, struck out five and walked three. Chad Qualls, Luke Gregerson and Erik Hamren each got three outs to complete the four-hitter.

San Diego, which reached double figures for the second straight game, also had Orlando Hudson drive in two runs and Cameron Maybin hit his eighth homer, a leadoff drive in the seventh.

New York starter Jonathon Niese (11-10) surrendered 10 hits over six innings, but allowed just three runs, two coming in the first. The left-hander struck out three and walked none.

The Mets, who have dropped 12 of 16 overall, lost for the 11th time in 14 games at Petco Park. New York, which won the first game of the three-game series on Monday night, has never won a set at Petco since the ballpark opened in 2004.

Luebke struggled with his control early, walking two batters in the first inning and another in the second. He hit Lucas Duda leading off the fourth, leading to the Mets' only run.

Jason Bay flied out and Scott Hairston bounced into a fielder's choice, but Ronny Paulino followed with a base hit and Ruben Tejada added an RBI double. Luebke then struck out Niese to end the inning.

Hundley and Hudson each had an RBI single in the first. Aaron Cunningham, the only Padres starter without a hit, added a sacrifice fly in the fourth inning.

Hundley and Fred Kendall (1973) are the only Padres catchers to triple twice in a game.

NOTES: With Jason Isringhausen getting his 300th career save Monday night at San Diego, the Mets plan to use RHPs Bobby Parnell and Pedro Beato in the closer role. Isringhausen might be used as an eighth-inning setup man, New York manager Terry Collins said. ... Tejada's RBI double in the fourth extended the Mets' streak to 14 consecutive games with at least one double. ... San Diego, last in the NL in batting average at .238, leads the league in runs scored since the All-Star break. ... Rookie RHP Dillon Gee (10-3), whose ERA has risen from 2.86 to 4.07 in his last 10 starts, will face the Padres for the first time in Wednesday's finale. Gee has failed to pitch beyond five innings in three of his last four starts. ... Mat Latos (6-11, 3.80 ERA) pitches for San Diego.