MIAMI -- Nationals infielder Chad Tracy will undergo surgery Thursday after an MRI exam revealed a tear in his right groin, and he could miss the remainder of the season.

"Any time they operate, it's probably a couple months anyway, if not the whole year," Washington manager Davey Johnson said. "He's going to be hard to replace."

Tracy was placed on the 15-day disabled list Monday and traveled to Philadelphia for a Tuesday MRI after he sustained the injury while running to second on a pinch-hit double during the Nationals' 8-4 win against the Braves on Saturday.

In 32 games this season, Tracy hit .265 with a .327 on-base percentage while serving as Johnson's go-to left-handed hitter in late-inning situations, a role that could now fall on Corey Brown, who earned his first career start Tuesday against the Marlins.

The injury to Tracy is just the latest in a long line of ailments to sideline Nationals players, as the team now has 14 players on the DL.

"I've never seen anything like it, and I'm kind of a dinosaur," Johnson said. "I've never had a club that had so many key players go down."

Nationals give Brown first career start

MIAMI -- When Corey Brown arrived at Marlins Park on Tuesday afternoon, he had no idea he would be starting his first big league game.

The left-handed-hitting outfielder was selected from Triple-A Syracuse on Monday and joined the team for its series opener against the Marlins. When he got to the visitors' clubhouse Tuesday and saw no lineup posted, he hit the weight room for a pregame workout. Upon his return, he looked up at the board and saw his name and the number seven next to it, signaling a start in left field.

"I just had that feeling inside, like, 'Man, today's that day,'" Brown said. "I have to make sure I go out there and don't get too overwhelmed."

After learning the news, Brown told his mom and five brothers, who quickly dispersed the news, resulting in Brown's Facebook page getting inundated with congratulatory remarks.

Monday's callup marked Brown's second stint with the Nationals. He was a late-season callup last year, but only had three pinch-hit appearances before developing a staph infection in his leg, ending his season. While grateful for the opportunity he had last year, Brown hopes to make the most of his latest opportunity and keep up the stellar numbers he put up in the Minors.

In 48 games with the Chiefs, Brown hit .297 with nine doubles, four triples and 12 home runs while driving in 30 runs.

"Hopefully I can just continue that here and help us get some more wins up," Brown said. "I just feel honored to be in the starting lineup with the first-place team in the division."