Novak Djokovic will have a case to be considered the greatest male tennis player of all time if he wins two or three more Grand Slams over the next year, according to Greg Rusedski.
Djokovic was the undisputed best player on the planet in 2016 when he held all four Major titles.
He then endured a difficult period, with a string of injuries and a loss of form seeing him drop out of the top ten of the rankings.
The 31-year-old marked his return to the top of the sport last month, beating world number one Rafael Nadal on his way to winning a fourth Wimbledon title.
This weekend, Djokovic beat Roger Federer in the Cincinnati final to become the first player to win all nine Masters 1000 events.
Speaking after Djokovics victory, Rusedski said the Serbian legend could still re-open the GOAT debate that is generally led by Federer and Nadal.
Asked what Djokovic must do to be considered the GOAT, Rusedski told Sky Sports: The US Open is possibly key for Novak.
If he wins [at Flushing Meadows next month] hes up to 14 Grand Slams. He could go on a streak and win two or three next year, then hes back in the mix.
In 2016 everyone was saying hes going to be the greatest of all time but then he had the injuries and the loss of form.
Its exciting. Weve got three stars in the mix. They will probably have one or two more years dominating then there has to be someone new coming to the party, surely?
Djokovic had lost five finals in Cincinnati before finally claiming a Western & Southern Open victory to complete his haul of wins in Masters 1000 tournaments.
This is obviously a special moment for me, standing here with a trophy at Cincinnati, the Wimbledon champion said.
Most of the finals here I lost to this great man [Federer], so thank you for letting me win here for once!
It was a tough match, maybe Roger didnt feel his best but hes a great champion and probably the best ever to play so its always a please to share the court with him.
I want to thank my team and family for their support. In the hard times they were there for me. It seems unreal to be back at this level.