"I'm very anxious about that," Riggleman said.
Thursday was a day of suspense at Nationals Park as the 22-year-old right-hander underwent his second MRI in less than a week. The results will be analyzed and announced on Friday, and the team is hoping they show nothing that will force the rookie phenom to sit out the rest of the season -- or worse.
Strasburg was pulled from Saturday's game at Philadelphia when he grimaced and shook his wrist after throwing a changeup. An MRI on Sunday confirmed the initial diagnosis of a strained flexor tendon in his forearm, but the test raised enough questions for the Nationals to order a more extensive MRI that uses an injection of dye into the arm.
Strasburg, the No. 1 overall pick in the 2009 draft, was placed on the 15-day disabled list Monday, the second time he's been sidelined in less than a month. This latest setback come in his third start since returning from the DL because of inflammation in the back of his right shoulder.
"The thing with Stephen, he was in my office yesterday saying, 'I could pitch tonight, I feel great,'" Riggleman said. "But you never know. Jordan Zimmermann last year felt like he could pitch through the whole situation, and it wasn't to be."
Zimmermann, another premier prospect, ended up having elbow ligament replacement surgery. He happened to be making his first start in the majors in more than a year Thursday night against the St. Louis Cardinals.
Another bit of happenstance: Thursday was the day the Nationals introduced Strasburg's successor as the No. 1 overall pick, 17-year-old slugger-to-be Bryce Harper.
Strasburg is 5-3 with a 2.91 ERA and 92 strikeouts in 68 innings with the Nationals and has thrown 123 1/3 innings total in the majors and minors this season. The Nationals were hoping he would throw 160 innings this year.