WASHINGTON -- The Nationals placed right-hander Jeremy Hellickson on the disabled list prior to Tuesday's game against the Rays with a "mild" right hamstring strain. Washington did not give a timetable for his return, but he is expected to miss a few starts.
Hellickson injured his hamstring during Sunday's 4-2 loss to the Braves, when he came up lame trying to cover first base in the first inning. His outing lasted just one out before he was forced to leave the game.
Because of off-days in the schedule, the Nationals do not need a fifth starter for about two weeks, so they could continue to use a four-man rotation for the time being. For now, they have a nine-man bullpen after they activated left-hander Matt Grace to take Hellickson's place on the roster and reinstated left-hander Tim Collins from paternity leave and optioned right-hander Jefry Rodriguez back to Double-A Harrisburg.

"We'll determine who our fifth starter's going to be when we need one," Nats manager Dave Martinez said. "We'll see where we're at. I don't want to strain the workload on the guys we got. These guys are doing really well, so when we feel like we need to pop somebody in there, we will."
Hellickson had helped stabilize the Nats' rotation as their fifth starter. In nine starts, he owned a 2.28 ERA with 34 strikeouts and just six walks.
Worth noting
• Daniel Murphy was re-evaluated by the Nationals on Tuesday and will continue rehabbing his surgically repaired right knee during his Minor League rehab assignment with Double-A. The team wants Murphy, who appeared to be running gingerly on his leg this past week, to continue getting comfortable in the field. Martinez said he thinks Murphy is fine running, but his biggest issue is stopping.