Before his college career began, Porter was largely considered the top prospect for the draft but that was before he lost almost his entire freshman season to injuries.
According to ESPN's Jonathan Givony, Porter has a strained hip and muscle spasms that are preventing him from getting out of bed, prompting the cancelation of a pro day workout in Chicago that had been scheduled for Friday.
However, there is one lingering concern that teams seem to have with regards to taking him in the NBA Draft.
According to Sam Amick of USA Today, Grizzlies executives recently met with Porter to evaluate his medical status and will "seriously consider" selecting him with the No. 4 pick.
Most teams are cautious about the back injury and whether it might be a problem throughout Porter's career.
Although Porter Jr. will not be able to showcase his talent on Friday, it is believed that the Pro Day will be rescheduled depending on how he responds to treatment over the next few days.
Porter missed nearly all of Missouri's 2017-18 basketball season after undergoing back surgery after the Tigers played just a couple games. He was able to return in March but appeared in just two games for the Tigers before they were eliminated Florida State in the first round of the NCAA Tournament.
The NBA draft will be held on Thursday, June 21.