The 37-year-old said on Wednesday he was still hopeful of playing Wimbledon, but two leading sports injury specialists were doubtful.
After analysing footage, Prof Arun Ranganathan, a leading trauma and orthopaedic spine surgeon who has helped a host of top athletes, said Murray most likely slipped a disc.
He said: “Looking at the video footage where he lost coordination and control over his leg, I feel it’s likely that he’s slipped a disc and it’s probably compressing on the nerve, and that’s when you get an acute weakness in the leg, which is what I suspect has happened.
“If my suspicion is correct, then probably he would not be ready to make it to Wimbledon.”
Murray rarely retires early from matches, but back injuries have been common in his career. He had surgery in 2013 and has often struggled during clay seasons.
After his first‑round defeat at the French Open last month, he revealed he would undergo treatment to address the soreness in his back.