Bernard Tomic’s former coach says he will struggle to make the world top 10 unless he changes his attitude.

Neil Guiney, who coached Tomic from the age of seven to 17, said the world No.17 needed to curb his behaviour if he wanted to consistently match it with the world’s best.

The 23-year-old apologised this week following reports he clashed with staff at a Gold Coast resort over a $20 court hire fee while practising for the Brisbane International.

Guiney said the incident showed the 23-year-old still lacked maturity.

“Habits die a bit hard,” Guiney told News Corp Australia.

“He’s got to watch that sort of thing because everyone else is watching.

“The further you go, the tougher it gets – not the easier.

“He’s a bit late at maturing … he’s at an age where he should be knocking on the door of the top 10.”

Guiney said Nick Kyrgios, who has also come under fire for his antics on and off the court, posed a major threat to Tomic’s chances of becoming one of the world’s 10 best players.

“If he keeps playing the way he has, he’ll hit the top 10 before Bernard,” Guiney said.

“Kyrgios is the one to keep an eye on.

“I think he (Tomic) has a bit of catching up to do.”

Tomic is still “light-years” away from world No.1 Novak Djokovic, Guiney said.

“When you look at the likes of Djokovic and so on, that’s world class.

“Bernard’s light-years away from say, Djokovic.”

In an all-Australian match-up, Tomic will tomorrow face world No.149 Jordan Thompson in the second round of the Sydney International.

Thompson, a two-time Australian Open wildcard playoff winner, didn’t think Tomic’s latest controversy would impact his performance.

“I highly doubt it will affect him,” he said.

“Off court is off court. On court probably just concentrate on the ball that’s coming.”