Andy Murray conceded he became distracted by Novak Djokovic's fitness problems during his Australian Open final defeat by the Serb.
World number one Djokovic won 7-6 (7-5) 6-7 (4-7) 6-3 6-0 as Murray was beaten in his fourth Melbourne final.
Djokovic, 27, had issues with his thumb and ankle in the opening two sets, then appeared to struggle with another leg injury as Murray led 2-0 in the third.
"I'm frustrated at myself for letting that bother me," the Briton, 27, said.
"The third set was frustrating because I got a bit distracted when he fell on the ground after a couple of shots," Murray added. "I dropped off for 10, 15 minutes there, and he got back into it.
"That's what I'm most disappointed about, not so much the fourth set because I think, especially at the end of it, he was just going for everything, and it was going in."
|BBC Sport tennis correspondent Russell Fuller|
|"Murray was quick to realise he blew his opportunity in the third set: the anger he directed at himself, his coaching team and his racquet derailed his challenge. It appeared a mental failing, rather than a physical one, as he was distracted by Djokovic's fatigue - which he suggested was not as debilitating as it appeared."|
Murray was aiming to win his third Grand Slam title after victory at the 2012 US Open and a home triumph at Wimbledon the following year.
He was also bidding to become the first man to win the Australian Open after three previous final defeats, but lost again to long-time rival Djokovic - who beat Murray in 2011 and 2013 - on Rod Laver Arena.
The Scot, playing in his first Grand Slam final since having back surgery in September 2013, battled back from a break down to win the second set and level the match before edging ahead early in the third.
Djokovic looked uncomfortable after every point, grimacing and limping, as Murray broke in the first game and held in the second.
However, the eight-time Grand Slam winner quickly managed to recover from the problem, winning 12 of the next 13 games to ease to his fifth Australian Open title.
"I have no idea what the issue was. He obviously looked like he was in quite a bad way at the beginning of the third set and came back unbelievably at the end of that set," he said.
"The way he was hitting the ball in the fourth and moving was impressive."