NEW YORK(AP) Angel Pagan picked the perfect moment to unveil some unexpected power.

Pagan hit a tiebreaking grand slam in the eighth inning for his first homer in two injury-plagued seasons with the Mets, and New York beat the Arizona Diamondbacks 9-6 on Saturday night.

''I don't remember being so excited,'' Pagan said. ''I was thinking of my wife. I was really pumped.''

Pagan's surprising shot gave him a career-high five RBIs. Brian Schneider hit an early RBI double and New York got strong relief work from Pedro Feliciano (4-3).

Justin Upton and Mark Reynolds hit long home runs for the Diamondbacks in a matchup of fourth-place teams who expected much more this season. Both clubs have been hampered by key injuries.

New York loaded the bases against Clay Zavada (2-3) with one out in the eighth on a walk and singles by pinch-hitters Omir Santos and Angel Berroa .

Pagan hit a drive into the left-field seats for his first career slam, giving the Mets a 9-5 lead and sending the crowd of 39,574 into a frenzy. After circling the bases, he came out for a curtain call.

''I just missed my spot with that fastball,'' Zavada said.

It was Pagan's first homer since July 15, 2007, with the Chicago Cubs against Houston. And it was the second time in six days the Mets hit a tiebreaking slam in the eighth inning. Pinch-hitter Fernando Tatis connected in Monday night's 7-3 win over Colorado.

Pagan has taken over as New York's regular center fielder and leadoff hitter lately because of injuries to Carlos Beltran and Jose Reyes .

''It's the opportunity you dream of,'' Pagan said.

And his teammates are thrilled to see him making the most of it.

''It's nice to see him put it all together and stay healthy and see what he can do,'' David Wright said.

Brian Stokes retired the first two batters in the ninth, then gave up a mammoth shot to Reynolds. The ball landed in the second deck of stands a little to the left of the 408 sign in center, one of the longest home runs at cavernous Citi Field.

In the first inning, the 21-year-old Upton, a first-time All-Star this season, hit his 20th homer, an impressive drive that sailed into the second deck in left.

''You watch their BP and it's an absolute show,'' Arizona starter Max Scherzer said. ''There's not a ballpark in the league that can hold them. Haven't seen one yet.''

Prior to Saturday night, the only visiting player to reach that deck here was Upton's brother, B.J., for Tampa Bay on June 21.

Reynolds has 30 homers, second in the majors behind Albert Pujols ' 34. He also dove over the tarp to catch a foul popup in the seventh.

Stokes walked his next hitter before Francisco Rodriguez retired pinch-hitter Miguel Montero on a popup for his 24th save in 27 chances. It was Rodriguez's first save opportunity since July 12.

New York had dropped two in a row following a five-game winning streak. The Diamondbacks had won four of six.

Mets starter Oliver Perez was erratic as usual, throwing 112 pitches through five innings. He struck out seven, walked five and left with a 5-3 lead, but Bobby Parnell squandered it in the sixth.

Gerardo Parra had a run-scoring groundout and Upton's two-out RBI single tied it at 5.

''Ollie competes when he gets out there,'' Mets manager Jerry Manuel said. ''He gets in those situations and finds a way to get out. I don't know if we can live with a walk per inning and a hit per inning and continue to be successful. So we have some work to do.''

Coming off a terrific outing against Pittsburgh, Scherzer touched 97 mph with his fastball and tossed three shutout innings before giving up four runs in a 38-pitch fourth. That was the end of his night.

''That's a frustrating outing,'' he said.

Arizona loaded the bases with nobody out in the third but failed to score.

NOTES: Diamondbacks SS Stephen Drew and C Montero were rested as manager A.J. Hinch stacked his lineup with seven right-handed hitters. Coming into the game, lefties were batting .216 against Perez while right-handers had a .307 mark. ... Hinch said the club wants RHP Tom Gordon (left hamstring) to start pitching well at Triple-A Reno before activating him from his rehab assignment. ''He does feel better,'' Hinch said. ... RF Jeff Francoeur has 18 RBIs in 18 games since joining the Mets in a trade from Atlanta. ... The Mets hadn't announced a starter for Monday night's series finale. They could call up RHP Nelson Figueroa from Triple-A Buffalo. ... Feliciano hasn't allowed an earned run in 24 1-3 innings at Citi Field.