Novak Djokovic caught even former coach Boris Becker by surprise in a return to dominance that has seen the Serbian add three more grand slams to his collection in recent months.
Twelve months ago, Djokovic was convalescing from elbow surgery and a series of early exits on his comeback to the ATP Tour led to suggestions he was in terminal decline.
But reuniting with long-time mentor Marian Vajda proved a significant cornerstone for Djokovic, who won Wimbledon and then the US Open last year before clinching a record seventh Australian Open crown last month.
Becker, who coached Djokovic for three years until the end of 2016, admitted he was just as taken aback by his old charge recapturing former glories.
Speaking in his role as a Laureus Academy member, the German told Press Association Sport: "It's remarkable.
"A year ago, he was just going through a break and elbow surgery and was just trying to find his feet again in tennis.
"For him to catapult himself back like that was not to be expected but he has a champion's mentality. He knows what it takes to win and he's fully on it."
The world number one's supremacy has given rise to the thought that he could overhaul Roger Federer's record of 20 grand slams in the near future.
Becker, though, believes the veteran Swiss is more than capable of adding to his tally and pointed out that the pair's great rival Rafael Nadal – with 17 grand slams to his name – could come into the reckoning.
- Djokovic is bidding to overhaul Roger Federer's (left) and Rafael Nadal's (right) tally of grand slam titles (Adam Davy/PA)
Becker said: "Who says Roger's not going to win more than 20? Maybe he's going to win Wimbledon this year.
"I wouldn't rule out (Djokovic going past Federer in grand slams). Can he do it? Yeah, but so can Rafa. Rafa has 17.
"There are big question marks. These three champions keep on winning and until they still play tennis, nothing is sure."
Andy Murray has recently undergone a second hip operation in a bid to prolong his career.
Murray had said ahead of the Australian Open last month that he intended to retire after this year's Wimbledon although Becker is not so sure.
He added: "This is an important decision. You have to take into consideration many things and, as far as I know, he has not officially retired."
– The Laureus World Sports Awards celebrate the most remarkable men and women from the world of sport along with their achievements from the previous calendar year. The Awards also showcase the work of Laureus Sport for Good, a charity which uses the power of sport to end violence, discrimination and disadvantage.
