PHOENIX - The day began with the Mets placing one of their best hitters on the disabled list. It ended with a reminder of just how much the latest injury will hurt.

Playing without Daniel Murphy for the first time, the Mets lost to the Diamondbacks, 7-2, just hours after the third baseman was placed on the disabled list Friday with a strained left quadriceps.

The Mets (30-26) failed to muster an answer for the Diamondbacks (26-28), who pushed ahead for good with a swift sixth-inning rally that spoiled lefty Jonathon Niese's best outing in nearly a month.

Michael Cuddyer hit his sixth homer and fill-in third baseman Eric Campbell snapped an 0-for-28 skid with an RBI single in the fourth. But it proved to be the Mets' final hit of the night.

Curtis Granderson struck out with the bases loaded in the fourth, squandering the Mets' best chance to pull away, and the Diamondbacks tagged the Mets' bullpen for four runs in the eighth.

"We've got to start capitalizing," manager Terry Collins said after watching his team dip a half-game behind the Nationals in the NL East.

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With the Mets leaning toward shifting back to a five-man rotation and one starter in danger of being shipped to the bullpen, Niese (3-6) allowed three runs in six innings, striking out eight.

It was the first time in his last four starts that he allowed fewer than four runs. But after a promising beginning, Niese's night unraveled in the sixth. Within the span of three at-bats, the Mets' 2-1 lead became a 3-2 deficit.

Diamondbacks slugger Paul Goldschmidt followed A.J. Pollock's ground-rule double by hammering a single to centerfield. The tying hit came on a good changeup below the knees. On Niese's very next pitch, Yasmany Tomas lined a go-ahead double, somehow keeping an inside cutter fair.

"They put some good swings on some pretty good pitches," Niese said.

Still, Niese's performance might have been enough with better run support from a lineup that struggled even before Murphy's injury.

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Murphy became the 14th Mets player to land on the disabled list since spring training. He joined a list that already included catcher Travis d'Arnaud and third baseman David Wright, who has been out for all but eight games this season.

The Mets sound optimistic about a shorter absence from Murphy, though with the way things have unfolded this season, even Collins knows better than to bank on it.

"It's not real serious," he said. "But David's hamstring wasn't very serious, either."

With Murphy down, Campbell will share time at third base with Danny Muno, who was recalled from Triple-A Las Vegas to take Murphy's spot.

"The news definitely could have been worse," said Murphy, who is hitting .283 with four homers and a team-high 29 RBIs.

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The Mets also played without catcher Kevin Plawecki. But after initial concerns that he was battling vertigo, he was listed as day-to-day with a virus that caused head congestion.