Troubled Australian tennis star Bernard Tomic has admitted to being on a "slippery slope" this year, but denied he was axed from the Davis Cup team by captain Pat Rafter due to his behaviour.
Tomic, 20, has fallen foul of Tennis Australia several times since reaching the quarter-finals of Wimbledon in 2011 and the organisation said on Thursday he would not be picked for the Davis Cup tie against Taiwan in February.
"It's not one specific incident, just an aggregation of his approach to the game," said Craig Tiley, Tennis Australia's director of tennis.
Australia's most recent Grand Slam winner, Samantha Stosur, also weighed in, telling Tomic he must "knuckle down" if he wanted to live up to his enormous potential.
Tomic said he had taken the comments on board.
"I'm young and I'm learning. You get to a point where you need to stop and I think it's a good bit of advice," he told the Ten Network late on Thursday of Stosur's comments.
"I'm working really hard and trying to push myself to become the best tennis player I can be.
"I've had a slippery slope the last year. It's changing me and I'll prove I'm going to be the best-ever player one day to play this game."
He denied being axed from the Davis Cup team, saying he was never going to be available as he planned to focus on ATP events in the United States.
"I was never meant to play that Davis Cup tie," he said.
"I spoke to Pat (about that). I'm going to use that time for training and to prepare for tournaments in America."
Rafter had been scathing of Tomic's performance in losing to Andy Roddick in the second round of this year's US Open, describing his final set capitulation as "disgraceful".
Tomic also admitted that he had given only "85%" in his 6-4, 6-0 defeat to German Florian Mayer at the Shanghai Masters in October.
In the same month, he was questioned by police after a fight with a friend on Australia's Gold Coast.
Tomic was found guilty last month of failing to stop for police on the Gold Coast in his high-powered, bright orange sports car and placed on a 12-month good behaviour bond.