There have been theories thrown out there as to why Djokovic made his coaching decision, but seven-time major champion John McEnroe offered a pretty hilarious theory this weekend.

If Novak Djokovic can win a 25th major title in the coming days, he will bolster his claim to be considered the greatest athlete in history, according to his new coach Andy Murray.

Novak Djokovic is widely regarded as one of the greatest tennis players of all time. He has won a record 24 Grand Slam singles titles, tying with Margaret Court.

MELBOURNE, Australia — Novak Djokovic and Andy Murray have known each other for a quarter of a century. They played from the age of 12, meeting 36 times as professionals, including 10 Grand Slam matches. Yet they've never been able to talk shop and freely trade all sorts of thoughts — about tennis and otherwise — until now.