Gio Gonzalez will take the mound against fellow NL All-Star R.A. Dickey and attempt to improve the Nationals to 10-4 July and give Washington a nine-game lead over New York, which has dropped six consecutive contests and nine of 12.
The Nationals also lead the teams' season series, 6-2.
Earlier this season, Dickey (12-1, 2.66 ERA) put together five consecutive starts without allowing an earned run, including 7 1/3 scoreless frames at Nationals Park on June 7. But since then, the knuckleballer has surrendered exactly five earned runs in three of his last four outings. His ERA in that span stands at 5.19.
"I know because of what's happened, everybody that we're facing now, they're really working the at-bats," Mets manager Terry Collins said.
On Saturday in Atlanta, the Braves reached Dickey for five runs on eight hits in five innings, but afterward he expressed confidence in a coming rebound.
"Every season has a storm or two in it," Dickey said. "You just kind of have to stay afloat. It'll turn."
The Nationals started Wednesday leading the Majors by solid margins in team ERA (3.16) and starters' ERA (3.17).
"I knew I was going to be pretty spoiled before Spring Training, knowing the caliber of talent that was here," manager Davey Johnson said. "I said we should contend in March."
Gonzalez, at 12-4 with a 2.93 ERA, has played a significant role in that success. The lefty hasn't allowed more than four earned runs in any of his 18 starts in his first season with Washington, and he has held the opposition to two or fewer runs 12 times.
Gonzalez was saddled with a loss on Saturday at Miami, but Johnson called his effort a "jewel," after he struck out nine and walked none in six innings, giving up two runs on two hits. It was the third time in Gonzalez's career that he struck out at least nine without issuing a free pass, and the first since August 2010.
Mets: Collins to 'mix and match' in outfield
Collins' lineup card for Wednesday's game included Jason Bay in left field, Andres Torres in center and Lucas Duda in right, but the Mets' skipper suggested that alignment could change frequently.
Bay recently returned from his second stint this season on the disabled list, while Duda is two days removed from receiving a cortisone injection in his strained left hamstring. The right-handed Scott Hairston and lefties Kirk Nieuwenhuis and Jordany Valdespin also are in the mix for playing time.
Collins doesn't care much for team meetings, but he called one about two hours before Wednesday's first pitch, in an effort to shake the Mets out of their recent slump.
"We've got to grind this thing out, because that's how we got to this point," Collins said. "This is an important part of it where this thing could go flat, and we're not going to let it."
Nationals: A collection of catchers
Injuries have forced Washington to deploy five different catchers this season. Opening Day starter Wilson Ramos is out for the year, and Johnson also has turned to Jesus Flores, Sandy Leon, Carlos Maldonado and Jhonatan Solano.
"I've said before, I like the depth of catchers in this organization, second to none [as far as] any other organization," Johnson said.
Flores has been the primary backstop since Ramos went down in mid-May, but he's hitting only .230 with a .608 OPS. Still, Johnson likes Flores' defensive skills behind the plate.
"I said, 'You're important to this ballclub, more important than what you do offensively. Grinding and punishing yourself as much as you do, just relax and try to enjoy it a little bit more,'" Johnson said.
Solano is dealing with an oblique strain and likely will end up on the disabled list. Leon, who is at Triple-A Syracuse, is the probable replacement.
Reliever Drew Storen, who has been on a Minor League rehab assignment, could be activated as early as Thursday.
Dickey is 3-1 with a 2.40 ERA in seven career starts at Nationals Park.
Gonzalez faced the Mets for the only time last June 22, giving up one run on four hits in seven innings as a member of the Athletics.
These two teams will meet for another three-game series, starting Monday at Citi Field.