'Pen session, but no start, for Stras Friday

ST. LOUIS -- Nationals right-hander Stephen Strasburg will throw a bullpen session on Friday, but he will not make his scheduled start against the Braves that night, according to manager Matt Williams. The news comes after Strasburg threw on flat ground on Wednesday without any pain in his back. Tightness in his back caused him leave Sunday's game against the Marlins after four innings.

"[Strasburg] has to get through the bullpen, which doesn't allow enough time [to make a start]," Williams said. "We have to make sure he feels good letting [the ball] go."

Strasburg allowed four runs on seven hits on Sunday. He surrendered a three-run homer to Justin Bour in the first inning and a solo shot to Derek Dietrich three innings later. The Nationals noticed that the velocity on his fastball was down, so they decided he was done for the day.

Right-hander Tanner Roark will start in place of Strasburg on Friday. Roark pitched two innings for Double-A Harrisburg on Monday before being taken out of the game in preparation for a potential start with the Nationals.

"We abbreviated [Roark's] start yesterday to give him three days' rest in line for Friday, if need be," Williams said.