Andy Murray withdrew from the Miami Open on Tuesday after suffering a "freak" groin injury which flared over the weekend.
The three-time Grand Slam winner, who had been granted a wildcard into the event as he works his way back from injury, arrived in Miami last week and trained without a problem on Thursday and Friday.
However the 33-year-old Scot woke early Saturday with pain in his groin which left him struggling to walk.
Although Murray said the problem had since improved, he was not fit enough to play.
"I have no idea what I did," Murray told the Miami Herald. "It's one of those freak things. Each day it has gotten progressively better, but it's not enough. I have not practiced since Friday."
Murray, a two-time winner in Miami and finalist in 2012 and 2015, could not hide his disappointment at his latest injury setback.
"I am really gutted," Murray said. "This is a place I have done so much training over the years. It's like my second home.
"Last time I played here was 2016 and so much has happened. In 2017 I had an elbow issues, last few years various issues with my hip. Last year, the day before I was supposed to travel here COVID stopped the tennis tour.
"Miami's been a place that has given me a lot, but this just wasn't meant to be."
Murray is one of several star names to have withdrawn from the Miami event.
Roger Federer, Rafael Nadal and Novak Djokovic all pulled out of the men's draw while former world number one Serena Williams withdrew on Sunday.
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