The 2008 Major League debut of Mulder lasted less than one inning on Wednesday evening. After striking out 2007 NL MVP Jimmy Rollins and walking two Philadelphia Phillies with a stolen base in between, Mulder left the game with "left shoulder irritation". He managed five strikes and 11 balls in his 16 official offerings.
The MRI on Friday was to help determine whether there are still structural problems with Mulder's left shoulder. The results will be known on Monday, the same day Mulder is scheduled to meet with a specialist.
"It's sad for him," Cards manager Tony La Russa said. "Clubs take hits, and I feel really bad for him -- he's worked so hard. First of all, he's truly a great pitcher, so he knows what he can do when he's healthy. To have that taken away from you, that's got to be very tough to live with. He's gone through a couple of years of rehabbing, which is painful and not only physical pain, but mentally, and right now there is no reward."
This has to be considered a major setback for the 30-year-old, trying to return from two shoulder surgeries. His teammates are concerned that it might signal an end to Mulder's career.
"We see him every day working out," Kyle Lohse said. "A lot of hard work has gone into that and it's unfortunate that he can't get it right. We're all rooting for him to get healthy and get back to the way he was."
"I've known Mark a long time," Troy Glaus added. "I was there when he was called up in Oakland -- playing against him in Anaheim, I played against him for years. Hopefully, this is just a blip on the radar. I don't know, I haven't heard anything, but he's been a great guy that I've known since I've been here, and I wish him all the best.
"He's been rehabbing a long time, and I think he felt like he was ready to go and then something happened. Hopefully, he can get back right and get back on the mound again."
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.