Nationals rookie pitcher Stephen Strasburg was scratched just moments before his scheduled start on Tuesday night against the Atlanta Braves with shoulder stiffness.

The 21-year-old had trouble “getting loose” during his warm-up session in the bullpen, according to Washington general manager Mike Rizzo, who quickly made the decision to scratch his prized youngster.

Strasburg threw a bullpen session during the team’s weekend road series in Milwaukee and played catch on Monday with no problems.

Beanballs blogFor more on Strasburg's injury, check out The Washington Examiner's Beanballs blog:» Nats Postgame - More on Strasburg after 3-0 win» Strasburg Injury Update

But when Strasburg struggled during his warm-up about 20 minutes before the start of Tuesday’s game at Nationals Park, pitching coach Steve McCatty reported that news to head trainer Lee Kuntz, who in turn notified Rizzo. The decision was made immediately – Strasburg would not start. The big crowd on hand to watch his 10th big-league outing booed when it realized Miguel Batista had taken the mound.

“Those are decisions I get paid to make,” Rizzo said. “Like I said, we’re going to err on the side of caution. I make the decisions and take the heat for it.”

Strasburg was examined by team doctors, who administered an MRI and X-rays. He passed both labral and capsule tests that check for shoulder weakness. The X-rays were negative. The MRI showed no rotator cuff damage and no changes from an initial MRI taken after Strasburg signed last August. He was diagnosed with shoulder inflammation and will begin a course of anti-inflammatories and treatment. Strasburg is still listed as day-to-day with no decision made on his next scheduled start on Sunday against the Philadelphia Phillies.

The team built an entire innings plan on limiting the risk to a first-year professional. Strasburg won’t go beyond 160 innings this season. As of Tuesday, he had pitched 55 1/3 minor-league innings and another 54 1/3 in Washington for 109 2/3 total. The No. 1 pick in the 2009 draft and one of the sport’s most heralded prospects in a generation, Strasburg is 5-2 with a 2.32 ERA.

“We’re going to use common sense and be cautious like we have,” Rizzo said. “This is a work load that he’s never seen before and we’re going to take it from there.”