Andy Murray "melted down and collapsed" in his Australian Open final loss to Novak Djokovic, according to two-time Melbourne finalist Pat Cash.
With the score at one set each, the Briton, 27, led 2-0 in the third before losing 12 of the next 13 games in a 7-6 (7-5) 6-7 (4-7) 6-3 6-0 defeat.
"He needs a good, hard look in the mirror and to get his head together," Australian Cash told BBC Radio 5 live.
"He has not put up a great fight. He hasn't. Don't put a rose tint on this."
Murray has won Wimbledon and US Open titles as well as an Olympic gold medal, but this defeat was his fourth in an Australian Open final and sixth in eight Grand Slam finals.
He was playing in his first major final since having back surgery in 2013, but Cash, a Wimbledon winner in 1987, felt the Scot would be disappointed with the manner of his defeat.
"He melted down, he absolutely collapsed," Cash said. "He will feel he let everyone down, but he has to look at it and say 'I can't do this again'.
"Things started snowballing for him once he lost concentration and in the fourth set everything went against him.
"I feel sorry for him and he is a seriously good player, but if he is to become a great player he has to fix this. He's got to focus on why he had the meltdown. If he works on that I can see him holding the Wimbledon trophy again."
Murray won his Wimbledon, US Open and Olympic titles with Ivan Lendl as his coach, and this was his first Grand Slam final while working with Amelie Mauresmo.
However, BBC commentator John Lloyd, who was a beaten finalist at the Australian Open in 1977, felt Murray's decline was similar to those the Scot suffered in the early stages of his career.
"He unfortunately went back to his old, pre-Lendl days, where things weren't going right and he'd blame his group and get negative," Lloyd said.
"Sometimes you can blow up in a match and immediately get back on track. But when Murray used to do it he would go into these periods where it would affect him for games on end and that's what happened again.
"But to give the match away because of those lapses is inexcusable from a person that has won two Grand Slams. It again showed his weakness and he has to correct that."