New York, which has lost four in a row and 10 of its last 13 after a 6-4 loss to the D-backs on Saturday night, will take the field for the finale on Sunday looking to end the series on a positive note.
"The message is the same, regardless of whether you're doing good or bad," Mets left fielder Jason Bay said. "But I think there are points where complacency can set in, and that's just kind of where we're at. And it's not OK. But at the same time, you try to get guys to go out there and do it on the field, and lead by example."
The D-backs, meanwhile, continue to make their surprising run for the National League West division title. Arizona's win on Saturday, the club's fifth straight, allowed it to maintain a two-game lead over the Giants.
But, to continue to make it a tough road trip for the Mets, starter Jason Marquis will have to right the ship.
The right-hander hasn't won since July 18, and continues to search for his first victory in a D-backs jersey since being traded by the Nationals last month. He surrendered four runs and nine hits to the Astros in his last outing on Tuesday.
"Obviously, you want to get off on the right foot with your new teammates, go out there and win some ballgames," Marquis said afterward. "I'm not putting too much pressure on myself. I'm just going out there and [trying] to pitch and throw the way I have been all year. Unfortunately, it hasn't turned out that way. But like I said, I'll keep working to get better and go back to the drawing board in between starts."
He'll take on left-hander Chris Capuano, who is 1-3 with a 3.77 ERA in his career against the team that drafted him in the eighth round of the 1999 First-Year Player Draft.
Mets: Izzy closing in on a milestone
Mets closer Jason Isringhausen needs just one more save to notch career save No. 300.
The veteran has converted six of his last seven chances, and would become just the 23rd Major League pitcher to reach the milestone -- joining Billy Wagner and John Franco as other Mets to accomplish the feat.
Isringhausen is 3-2 with a 3.54 ERA and six saves this year.
Bay has reached base safely in his last 14 games, after reaching on a second-inning error on Saturday.
D-backs: Shutting the door
J.J. Putz and David Hernandez have combined to covert all 12 save opportunities since the All-Star break.
The D-backs announced on Saturday that they placed infielder Xavier Nady on the 15-day disabled list (fractured left hand) and signed free-agent infielder Lyle Overbay, who was released by the Pirates this month.
The Mets have won 33 road games already this season, after winning just 32 in 2010.
Arizona's Paul Goldschmidt has reached base in 10 of his 11 games since joining the team on Aug. 1.
New York won 13 straight games in Arizona from 2004-07, but has won just three of its last 12 in the desert since.