Stephen Strasburg's phenomenal rookie season has hit a roadblock.

Strasburg was scratched from Tuesday night's start at Nationals Park against the Atlanta Braves, as Nationals general manager Mike Rizzo made the decision after Strasburg had trouble getting loose in the bullpen before the game.

Strasburg paused during his warmups and, after consulting with catcher Ivan Rodriguez and pitching coach Steve McCatty, ceased his throwing and left the bullpen about 15 minutes before game time. Rizzo told news reporters during Tuesday's game that Strasburg was scratched for precautionary reasons and X-rays and an MRI are planned.

Long reliever Miguel Batista started the game in Strasburg's place. Rizzo termed the move "erring on the side of caution" and did not specify if the concern was with Strasburg's elbow or shoulder.

"He's never had this workload before. I made the executive decision of saying if you can't get loose, I'm not going to let you pitch," Rizzo said on the Nationals' Mid-Atlantic Sports Network broadcast. "He hates to disappoint fans, but that's my call I have to make. "

Strasburg has pitched 54 1/3 innings at the major league level this season and was coming off a 97-pitch outing in his last start, when he gave up three earned runs in 5 2/3 innings and beat the Cincinnati Reds. Including his stints at Class AA and Class AAA, Strasburg has pitched 109 2/3 innings, and the Nationals aimed to end his rookie season after he reached 160 total innings.

"As we have throughout the process, we're being very careful with him," Rizzo said. "He wants the ball every fifth day, but it's my job to protect him."

Rizzo indicated there were no complications in his normal side session two days after beating the Reds.

Overall, he is 5-2 with a 2.32 ERA with the Nationals, and has struck out 75 batters in 54 1/3 innings.

By Gabe Lacques