SAN DIEGO -- The Seattle Mariners were leading the San Diego Padres by a run through six innings when manager Lloyd McClendon decided 22-year-old Taijuan Walker had gone far enough, even with a shutout intact.

Walker did more than enough, holding the punchless Padres to one hit. The Mariners then piled on against James Shields and the Padres' bullpen, winning 7-0 Wednesday in their second straight shutout against the Padres.

Struggling Robinson Cano and Nelson Cruz each homered. Cano had four hits and drove in three runs while Cruz connected for his 20th homer on his 35th birthday.

Walker (7-6) struck out seven and walked none. He combined with four relievers on a three-hitter.

"This is a young pitcher that's going deep into a lot of ballgames. At some point you have to protect him," McClendon said. "He may not like it, but 12 years from now when he's still pitching, he'll thank me. He'll say, `The old man knew what he was doing."

Walker said he was a bit surprised he came out, "but we had the opportunity to score, with this being against the National League, so we'll take all the runs we can get and we ended up scoring there."

"It's part of the National League. I thought it was a great team win and the offense did really great and the bullpen came in and shut the door," he said.

Rookie Mike Montgomery threw a one-hitter against the Padres on Tuesday night. They have been blanked 13 times this year.

James Shields (7-3) failed for the fifth time to get his eighth victory. He's lost three straight starts.

Cano hit an opposite-field homer to left leading off the sixth. His fifth home run came after he'd been 0 for 10 with four strikeouts in his last three games.

"Hopefully it's about the team and not about me getting hot or swinging the bat good, it's about winning," Cano said. "We've got to get going."

Cano improved to 37 for 90 (.411) lifetime against Shields, with five homers and 16 RBI. The 37 hits are the most by an active player against an active pitcher.

"He's a guy that goes after hitters, so he's a guy you've got to be ready for his first pitch. He's one of the best in the game," Cano said.

McClendon thinks this will jump-start Cano, who came in hitting .238.

"I can't think of a better way. Four hits with a home run, some ribbies and scored some runs," the manager said.

The Padres, meanwhile, didn't get any.

"Their pitchers went out and did their jobs," San Diego's Justin Upton said. "They both went out and pitched great games."

"It's frustrating because no one likes to lose, especially the way we lost. We're not getting any hits, we're not scoring any runs. It's frustrating for all of us and we have to figure out a way to do better," he said.

Interim manager Pat Murphy, who replaced the fired Bud Black on June 16, said: "Coming in new to the club, the thing that has shocked me is how tense everyone is."

Shields was pulled after walking the bases loaded with two outs in the seventh and Cano greeted Frank Garces with an RBI single. Dustin Ackley, who had pinch-hit for Walker, was thrown out trying to score from second.

Cano hit an RBI double off Kevin Quackenbush with one out in the ninth. Cruz followed by greeting Marcus Mateo with a two-run shot to left.

Walker allowed Yonder Alonso's single with one out in the fourth and also hit Derek Norris with a pitch, but otherwise kept the Padres off the bases.

Walker's winning streak includes four road starts during which he's allowed just three runs in 26 innings.

San Diego's only other hits were Yangervis Solarte's double with two outs in the seventh off Mark Lowe and Jedd Gyorko's single leading off the eighth against Fernando Rodney.

Solarte doubled with one out in the seventh inning Tuesday night for San Diego's only hit against Montgomery.

Shields allowed two runs and four hits in 6 2/3 innings, struck out seven and walked four. The Padres have scored only three runs in his last four starts.

TRAINER'S ROOM

Padres: INF Will Middlebrooks is still day-to-day with an ankle injury, although he remains available for pinch-hitting duty.

UP NEXT

Mariners: Seattle opens a four-game series at Oakland on Thursday night, with LHP Roenis Elias (4-5, 4.25) scheduled to start against LHP Scott Kazmir (4-5, 2.79).

Padres: San Diego starts a 10-game, three-city trip that takes it to the All-Star break. RHP Tyson Ross (5-7, 3.57 ERA) is scheduled to start the opener of a four-game series at St. Louis on Thursday night.