Roger Federer warned temperamental Australian Nick Kyrgios on Tuesday that he would never fulfil his potential without the work ethic to go with his talent.
The 23-year-old Kyrgios made another contentious exit from the Shanghai Masters on Monday after a running argument with the chair umpire who suggested his efforts were "borderline".
The 38th-ranked Kyrgios was on the end of a surprise first-round loss to the American qualifier Bradley Klahn, the world number 104 winning 4-6, 6-4, 6-3.
It is the third time in as many Shanghai appearances that Kyrgios has departed the Masters 1000 event under a cloud.
Federer, who is the top seed and the reigning champion in Shanghai, called Kyrgios "a great player". But he also sounded a note of caution.
"I think it's really up to him where he wants to go and what his potential really holds," said the 20-time Grand Slam winner.
"We don't really know and I don't think he really knows exactly what his potential is.
"And only through understanding work ethic and scheduling and whatever it might be, creating the right team around himself, only then can you unlock the potential, really."
Federer, who admitted that the hard graft did not necessarily come naturally to him either, backed Kyrgios to "win bigger tournaments and do all these things".
"But there is still a process in place that he needs to do like any other player needs to go through in order to be successful," he added.
Australian doubles great Todd Woodbridge said the scheduling of Shanghai, a compulsory tournament at the tail-end of the season, seemed to be a problem for Kyrgios.
"Nick plays his best tennis when he's fresh, when he's enjoying himself and he's engaged," said Woodbridge, according to the Melbourne Age.
"When he has to go somewhere and that isn't the case, we see him a little jaded and we see him play the way that he did... Scheduling is huge for him. He gets tired and then it's regrettable for him."