PHOENIX - A Mets roster that has long been stretched past its breaking point now faces the prospect of another critical loss.

In a 6-2 victory over the Diamondbacks Thursday night, Matt Harvey earned his first win in more than a month and the slumping John Mayberry Jr. enjoyed a breakout game. But all of it came after Daniel Murphy left the game before the third inning with a tight left quadriceps. He will have an MRI exam Friday.

"You never want to go down," said Murphy, who injured himself running out a grounder. "It is frustrating. But we're not the only team in the major leagues dealing with injuries right now."

Of course, few teams have dealt with more.

Harvey (6-3) hoped to provide some temporary relief, allowing two runs in seven innings to win for the first time since May 1. He struck out nine and walked one. The damage was limited to solo homers by Paul Goldschmidt and Jarrod Saltalamacchia.

"I kind of got angry that my last couple of starts weren't very good," Harvey said. "I needed to put an end to that."

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Run support proved to be no problem thanks to Mayberry, who in a spot start collected a career-high four hits, including a two-run homer in the ninth that provided an important cushion.

"Obviously, the results haven't been what I like," said Mayberry, who entered play hitting .137. "But this is a start in the right direction."

Jeurys Familia worked through three wild pitches to record the final five outs for his 16th save.

The Mets won for only the second time in their last 11 road games -- but it might have come at a steep price. Already riddled with injuries, they can ill afford another extended absence, particularly from one of the most productive bats in an underwhelming offense.

Murphy, who doubled in his first at-bat, has reached base safely in 14 straight games. During that span, he's hitting .412.

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Before the game, manager Terry Collins shifted Murphy to third base to supplant Ruben Tejada, who moved to second.

The Mets stopped short of a full reshuffling. Range-challenged shortstop Wilmer Flores remains entrenched, partly because Collins believes a move would create controversy and distraction. Said Collins, "We're trying to play baseball here and stay off the back pages."

Still, Murphy's best position is third, which conceals his range issues. And Tejada is a shortstop, making the middle infield a more natural fit. Those moves alone promise to bolster the infield defense. "I think it makes us a better ballclub immediately," said Murphy, who discussed the idea with Collins and third-base coach Tim Teufel. "So we're going to do it."

Collins said he has been weighing the shift for more than a week and took action once it became clear that David Wright's back injury will keep him out for several more weeks.

But by the third, Murphy had left the game. He was replaced by Eric Campbell, who extended his hitless streak to 27 at-bats.

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Dillon Gee has been the only Met to come off the disabled list this season and is expected to make his next start in the six-man rotation. Harvey downplayed any issues with the plan, even though his next start could come with two extra days' rest. "It's my job to stay focused, to stay ready," said Harvey, who generally prefers to avoid extra rest.

Even with Gee back, a dozen players are on the DL, including Travis d'Arnaud and Dilson Herrera. Both played in rehab games with Class A Port St. Lucie Thursday night but neither is expected back in the coming week.