Washington's Jordan Zimmermann was looking forward to taking the ball for the first time this season after an impressive spring training.
Unfortunately flu-like symptoms will push his first start back.
Zimmermann, who went 19-9 with a 3.25 ERA last season and compiled a 0.50 ERA over 18 innings this spring, is part of a solid group of starters that includes Stephen Strasburg, Gio Gonzalez, trade acquisition Doug Fister and Roark.
Roark was 7-1 with a 1.51 ERA in 14 games - five starts - as a rookie in 2013. The right-hander, who had a 3.29 ERA over 13 2-3 innings in four Grapefruit League games, made his second start against the Mets on Sept. 12, yielding two runs in six innings of a 7-2 win.
Strasburg struck out 10 in the Nationals' 9-7 comeback win over New York in Monday's 10-inning opener before Gonzalez homered in his first start for the second straight year and tossed three-hit ball through six innings in a 5-1 win Wednesday.
Ian Desmond also went deep and Jayson Werth had four hits for the Nationals.
While Washington's starting rotation appears to be solid, it now has a question mark behind the plate. Catcher Wilson Ramos is expected to miss about four to six weeks after having surgery Wednesday to repair a broken hamate bone in his left hand. The team's No. 1 backstop batted cleanup Monday and felt pain in his hand during an at-bat before being removed in the seventh.
"We don't know whether it started out as a stress fracture or what," manager Matt Williams said. "It's rough to go through something like that, but what can you do now except rehab? He's focused on that."
Jose Lobaton was behind the plate Wednesday night and Washington recalled switch-hitting catcher Sandy Leon from Triple-A Syracuse before the game. Williams said choosing his starting catcher will be "a day-to-day process" until Ramos returns.
With New York losing Matt Harvey for the entire season after elbow surgery, scheduled starter Zack Wheeler has the potential to emerge as the Mets' top starter in his second season.
The No. 6 pick in the 2009 draft by San Francisco, the right-hander went 7-5 with a 3.42 ERA in 17 starts for the Mets as a rookie after dropping three of his last four decisions. He went 1-2 with a 3.93 ERA against Washington, which roughed him up a bit with five earned runs in 2 2-3 innings in an exhibition game March 25.
"He's got to realize how good he can be," manager Terry Collins said. "There's going to be times, as we talked about last year, where he can just take over a game. And he knows that."
New York may need to squeeze as many innings as possible out of its rotation with an already-suspect bullpen that suffered a blow with the loss of closer Bobby Parnell.
The Mets placed Parnell on the 15-day disabled list Wednesday with a partially torn elbow ligament, and he will be sidelined until at least late May. New York also selected the contract of veteran right-hander Kyle Farnsworth from Triple-A Las Vegas.