SAN DIEGO – The super-subs saved the day, the series and the homestand for the San Diego Padres.

Damian Jackson hit a game-winning home run leading off the eighth inning, his second of the day and his fourth hit, as the Padres beat the Seattle Mariners 5-4 on Sunday to take two of three games. He had three RBIs, scored three times and stole a base.

Xavier Nady homered for the third straight game, and Mark Sweeney added an RBI hit.

None are regular starters, but all have come up big for the Padres, who continue to lead the weak N.L. West despite several injuries and a streaky June.

Before the game, the Padres put first baseman Phil Nevin on the disabled list, where he joined catcher Ramon Hernandez and second baseman Mark Loretta, as well as their winningest pitcher, Adam Eaton. Center fielder Dave Roberts has missed two games with a sore left knee.

“When that happens, you need guys to go out there to get the job done, and that’s what’s happening right now,” manager Bruce Bochy said. “These guys are really softening the blow of the huge losses we’ve had here, with their type of play. Jackson, Sweeney and Nady, they won the game for us.”

Jackson, one of the last cuts of spring training, came up from Triple-A on May 3 after infielder Geoff Blum joined shortstop Khalil Greene on the DL. Jackson has seen most of his action at second base after Loretta strained his left thumb on May 18, requiring surgery.

Jackson’s second homer, on a 3-1 pitch from Julio Mateo (2-3), broke a 4-4 tie. Jackson also hit his third career leadoff homer, off Joel Pineiro. He has three homers this year.

“Damian Jackson just killed us,” Seattle’s Bret Boone said.

Mariners rookie catcher Rene Rivera hit his first homer, a three-run shot off Woody Williams with two outs in the seventh that tied the game at 4.

“It was a great feeling,” Rivera said. “I was trying to hit the ball to just get a base hit. When I hit the ball, I said: ‘I’ve got a chance.’ “

With the Padres leading 4-1, Williams allowed consecutive two-out singles to Bret Boone and Mike Morse before Rivera hit a 2-1 pitch into the seats in left.

Boone also homered off Williams, in the fifth.

Pineiro got his seventh no-decision in eight starts. He allowed four runs and seven hits in six innings, struck out three and walked none.