The Miami Marlins' Jose Fernandez was ecstatic after learning he made the NL All-Star team.
Fernandez takes the mound Saturday night opposite Haren, who tries to snap the longest losing streak of his career.
Despite having never played higher than Class A, Fernandez (5-5, 2.83 ERA) is quickly making a name for himself. The 20-year-old right-hander has struck out 99 in 98 2-3 innings and ranks among the NL leaders in opponent batting average (.194).
"I'm not really thinking about how everything has come," Fernandez, who will be the Marlins' lone representative at Tuesday's All-Star game, told MLB's official website. "It's incredible. It's pretty fun to get a chance, first, to be in the big leagues. And now they trust me to be on the All-Star team. That's something I really can't explain. It's incredible."
Fernandez had gone 3-1 with a 1.34 ERA over a six-start stretch before yielding three runs, four hits and a season-high four walks in six innings Sunday in a 3-2 loss at St. Louis.
"He gave us a chance and that's what he's done really almost every time this year," manager Mike Redmond said.
Fernandez, who is 3-0 with a 1.47 ERA over eight home outings, will try to bounce back in his first appearance versus Washington (47-46).
"I feel great, I feel strong," he said. "Nothing to worry about. Five days, go back out there and do what I do."
Haren (4-10, 6.00), meanwhile, is struggling through the worst big league season of his 11-year career. The right-hander, who was an All-Star selection from 2007-09, owns the NL's highest ERA among pitchers with at least 85 innings.
In his first start back since missing two weeks with shoulder inflammation, Haren allowed two runs, seven hits and three walks in five innings Monday in a 3-2 loss at Philadelphia. He is 0-7 with a 6.66 ERA in nine outings since May 14, with the Nationals losing each time.
"I felt good but obviously I would've preferred the outcome to be different," he said.
Haren gave up a season high-tying seven runs - three earned - in 4 1-3 innings April 16 in an 8-2 loss at Miami, dropping to 1-4 with a 3.43 ERA in six starts against the Marlins. Placido Polanco is 9 for 25 in their matchups.
NL-worst Miami (34-57) is seeking a season best-tying third straight win after taking Friday's opener 8-3. Marcell Ozuna had three RBIs and Giancarlo Stanton hit a two-run homer as the Marlins tagged Stephen Strasburg for a career-high seven earned runs.
"I don't think anybody anticipated that. Fortunately for us we were able to come out there and have some great at-bats," said Redmond, whose club has won nine straight and 15 of 19 overall when Ozuna drives in at least one run.
The Nationals have gone 2 for 29 with runners in scoring position during a 1-4 stretch. Bryce Harper is 2 for his last 15 and Ryan Zimmerman is 1 for his last 16. That one hit, though, left the yard.
Washington, last in the majors with a .215 average on the road, has dropped eight of 13 in Miami.