Allan Donald has revealed England bowler Steve Harmison has been suffering from severe doubts about his own ability in the Test arena.
Donald was England's bowling coach last summer and tried to help Harmison rediscover the form that took him to number one in the world.
With injuries to Matthew Hoggard and Andrew Flintoff, Harmison became England's senior bowler but the South African said the Durham man could not handle the expectations put on him.
Donald claims Harmison's self-doubt was what caused him to start struggling with his line and length.
"I've never seen a bloke as low as Steve was during that Manchester Test against West Indies," Donald told the Daily Mirror.
"When he came off the field he admitted he was dead scared. He was scared of letting the ball go and he soon realised that Michael Vaughan could not turn to him."
Harmison has performed well for Durham so far this summer and is the leading wicket-taker in Division One of the County Championship. But Donald doubts if the fast bowler would be able to replicate that form in a Test match.
"Sometimes I feel that there is a fear of being on that massive stage. It could be," added Donald.
The South African feels Harmison will never get back to his world-beating best as the man himself does not know how it happened and therefore can not re-trace his steps.
"Does he know and fully understand how he became the world's number one bowler? Or did he just bowl?
"I had my doubts as to whether Harmy really understood how he had got there. That's why inconsistencies creep in."