WASHINGTON, July 28 (UPI) -- Washington pitching sensation Stephen Strasburg said Wednesday he was not sure when he would next make a start for the Nationals.

Strasburg, whose much-anticipated rookie season has been an outstanding success to date, was scratched from his scheduled start Tuesday because of tightness in the shoulder of his throwing arm.

His next scheduled start would be Sunday.

"I feel a lot better," Strasburg said prior to Wednesday's Nationals' meeting with Atlanta. "My range of motion, after going through some stretching and everything, is starting to come back to me.

"I made some big strides today. I'm not going jump the gun. I'm at a point right now in the season where I'm going into unchartered territory. I have to be smart and look at the big picture."

Strasburg (5-2) has a 2.32 ERA in 54 1/3 innings. Counting his time in the minor leagues this year, he has worked 109 2/3 innings. He pitched 109 innings during the 2009 collegiate season with San Diego State.