The world's most successful sprint coaches have criticised Mark Lewis-Francis' attitude on the eve of the World Championships.
Lewis-Francis set his personal best over three years ago
Maurice Greene's mentor John Smith said: "If you want to be successful, you have to be in an atmosphere that's frightening - but Mark's comfortable."
Trevor Graham, coach to Olympic champion Justin Gatlin, said: "He's not even close to fulfilling himself."
Lewis-Francis, 22, has failed to lower his personal best in three years.
He won World Junior 100m and 200m gold back in 2000 and was the fastest 17-year-old in the world, but has struggled to turn that raw potential into medals as a senior.
Earlier this year he was given a public warning after testing positive for cannabis, although he claimed he was the victim of passive smoking.
Graham, who also coaches Olympic 200m champion Shawn Crawford, said: "Mark hasn't improved in a while. And if he's not improving, he needs to make a change and quickly.
"I watch him all the time. If I was him, I would do anything in my power to be in the right situation as quickly as possible so I could learn what I needed."
Lewis-Francis is coached by Steve Platt, the man who has guided him from his first teenage days at Birchfield Harriers in Birmingham.
He has been attracting attention from Smith and Graham for some time, both coaches savvy enough to understand that their own reputations depend on having the brightest talents under their control.
Graham said: "I watch Mark sometimes in their warm-up, and it's like he's telling the coach what he's going to do.
"If the coach is listening too much to the athletes, either the coach or the athletes doesn't have a clue."
Smith, who coached Greene to Olympic and World 100m gold and the world 100m record, said: "A change in venue would be good for him.
"If Mark wants to come, my door is open for him. But unless he makes that first step, I won't know if he's serious."