Hernandez will take the mound for Washington as it looks to complete a three-game sweep of the slumping New York Mets at Shea Stadium.
After starting the season 13-4 with a 3.27 ERA in his first 23 starts, Hernandez is 2-3 with a 5.86 ERA in his past eight outings, including a 4-0 loss to NL East-leading Atlanta on Saturday. Hernandez allowed four runs and seven hits over eight innings.
He is 2-1 with a 6.38 ERA in four starts against the Mets this season.
The Nationals are three games behind wild card-leading Florida and Philadelphia.
Washington has won the first two games of a six-game road trip after losing five of its previous six.
Carlos Beltran had three hits and two RBIs for the Mets, who lost for the 14th time in 17 games.
“We’re just trying to keep our heads above water,” outfielder Cliff Floyd said. “Like I said, we’re in last place. The organization and the team are headed in the right direction and at the same time we’ve got to finish strong. It’d be a shame not to.”
Jae Seo will pitch Thursday’s finale, looking to continue what has thus far been a very successful audition for a spot in next year’s rotation.
Though he suffered a 3-2 defeat at St. Louis on Saturday, Seo has won seven of nine decisions as a starter this year. He has allowed three runs or fewer in nine of 10 starts.