Here's some potentially concerning news for the Nationals. After facing only one batter in Sunday's key series finale against the Braves (WAS-ATL GameTracker), Nats right-hander Jeremy Hellickson exited the game with an apparent injury. Hellickson appeared to injure his right hamstring while running to cover first base. MLB.com has video of the injury. 

There's no word yet on the severity of injury, but it was obviously enough to cut short Hellickson's outing after a mere four pitches. He was replaced by right-hander Jefry Rodriguez, who in doing so made his major-league debut. 

The Nationals have of course been hit hard by injuries this season. Most notably, center fielder Adam Eaton, who underwent ankle surgery after playing in just eight games, and second baseman Daniel Murphy, who's yet to play after offseason knee surgery. Losing Hellickson for any length of time -- hamstring injuries are often slow to heal -- would also be a blow. This season, Hellickson has pitched to a 2.28 ERA in 43 1/3 innings with 34 strikeouts against just six walks. As such, he's been a valuable presence in the D.C. rotation. 

In terms of potential replacements, top pitching prospect Erick Fedde would seem to be an option. However, that may not be tenable, at least right away: 

The good news for Washington is that they have four off days over the next 11 days, so there's plenty of flexibility in the schedule if they need to shuffle.