Novak Djokovic could become the unanimous GOAT of tennis and make the age-old debate meaningless.

That's according to Roger Federer's former coach Ivan Ljubicic who was commenting on the Serbian superstar's recent successes.

Earlier this month, Djokovic won the French Open to make it a record 23 Grand Slam titles. That win notably saw him overtake Rafael Nadal (22) with many anointing Djokovic the greatest tennis player of all time if they didn't already do so.

It will be even more unanimous if Djokovic goes on to complete the calendar slam with wins at Wimbledon and the US Open later this year.

But for now, Ljubicic believes there's no question that Djokovic is the most successful tennis player of all time. But when it comes to the greatest, he believes things still remain subjective.

“I feel that Novak is the most successful already, but the word ‘greatest’ implies subjectivity and personal preference,” Ljubicic said in an interview with Sport Klub (via Sportskeeda). “I think that’s good, to be honest – everybody has a preferred GOAT and let the discussion begin.

“If we look at other sports, for example is there a (definitive) GOAT in football. In basketball everybody agrees that it’s Michael Jordan, but he’s not the one with the most trophies. It’s someone that influenced you personally mostly: for a third of the world it’s Federer, for the other third of the world it’s Nadal and for the final third it’s Novak.”

That said, there is a way Djokovic could settle the debate for good once and for all.

For Ljubicic, that's by creating enough separation between him and Nadal and winning as many as five to ten more Grand Slam titles than the rest of the competition.

“If Novak wins a few more Slams – which seems likely at this point – then the debate becomes meaningless,” he added. “If Novak ends up having five to ten more than the others, we won’t have conversations like this anymore.”

Although Novak Djokovic is 36 years of age, with the way he's going, he could more than definitely add a few more Grand Slam titles to his record.

Whether he could reach 30 — like some are hoping for — remains to be seen.

After all, nobody expected anyone to reach 20 a few years ago, so if Djokovic could even close to 30, it's hard to see anyone debating against him being the GOAT.