PHOENIX -- Trent Oeltjen had no idea playing in the big leagues would be this much fun.
"It's been unreal," said Oeltjen, the 25th Australian to play in the major leagues.
"The last couple of days, I have to wake up and pinch myself," Oeltjen said. "They are getting to see highlights back home. I'm getting a lot of phone calls and messages. Everyone here has made me feel comfortable. I'm glad I can go out and help the team win a few games."
Oeltjen, who homered in his major league debut Thursday in Pittsburgh after his contract was purchased from Triple-A Reno and connected again Sunday, also had one of Arizona's five doubles.
Catcher Miguel Montero had three doubles while winning pitcher Doug Davis had perhaps the biggest hit, a soft liner that got past diving Mets center fielder Angel Pagan to drive in the final two runs of a three-run second inning for a 3-0 Arizona lead.
"I hit it just soft enough to get it under his glove," Davis said.
Davis (7-10) gave up two runs and four hits in seven innings to win his third straight decision. He won his first back-to-back starts since having surgery to remove a cancerous thyroid in April 2008. He beat the Los Angeles Dodgers on April 8, two days before the surgery, and beat Atlanta on his return May 23.
Davis improved to 3-1 in his career against the Mets.
"He battled very well," Arizona manager A.J. Hinch said. "He pitched as a quality starting pitcher should. His methodical approach to pitching is a testament to his preparation. He understands how to change a batter's timing, how to change eye levels, how to make pitches. He creates his own luck. He creates his own outs. He's having a terrific year."
The Diamondbacks (51-62) beat the Mets (52-60) for the fourth time in five meetings this season after taking three of four at Citi Field from July 31-Aug. 3.
Arizona has won eight of its last 12 games.
Arizona first baseman Chad Tracy had two run-scoring singles, the first after Oeltjen's double to left-center field leading off the fifth.
The Mets also committed two errors, one on an errant throw by Pagan and another when shortstop Anderson Hernandez threw to an uncovered first base while attempting to complete a double play.
"We were a bad team tonight," Mets manager Jerry Manuel said. "We didn't pitch well. They had a couple of hustle plays on us. Very poor game. Very poor effort on our part. There has to come a time where there is some consistency. We are just not getting that."
Pelfrey (8-8) dropped to 0-4 in five starts against Arizona while losing his second straight meeting of the season. Pelfrey had not pitched since a 5-2 loss to the Diamondbacks on Aug. 2, being pushed back to be with his wife, Angela, for the birth of their first child -- a boy, Chase -- on Thursday.
"I named my kid Chase, and I got my first loss in Chase Field," Pelfrey said. "It gets back to executing pitches. I left balls up, and they hit them."
Fernando Tatis had a two-run triple to close Arizona's lead to 4-2 in the fourth.
Manuel indicated that third baseman David Wright likely will not start Tuesday. He has played 111 of the Mets' 112 games this season.
"I think it will help me," Wright said. "This had been quite a grind, mentally and physically. You want to play every game, but sometimes it is in your best interest and the team's best interest to get a fresh set of legs out there."
Mets left-hander Billy Wagner on a rehab assignment threw a scoreless inning at Class-A St. Lucie on Monday. He gave up one hit and had a strikeout while throwing 14 pitches. He is scheduled to pitch again Wednesday, a Mets spokesman said. Wagner has made four scoreless appearances for St. Lucie, with six strikeouts and no walks in four innings. ... Arizona infielder Rusty Ryal, whose contract was purchased from Triple-A Reno when Chris Young was optioned to the minor leagues, had a pinch-hit single in the eighth inning in his first major league at-bat.