Andy Murray and Novak Djokovic will struggle to come back as strongly as Federer and Nadal - Moya

The Briton and the Serb have been out for much of 2017 with hip and elbow injuries respectively and Moya, who is Nadal's coach, thinks the exploits of his charge, who is world No 1 and US Open champion, and Federer, who won the Australian Open and Wimbledon, will be tough to match.

"You never know what will happen", said Moya.

"The more players with chances to win important tournaments, the much better for everyone. Rafa will be prepared to be willing to start. It's going to be a very exciting year."

Moya also insisted that despite Nadal's achievement of returning to the pinnacle of the sport, the focus is a break after the Spaniard was forced to withdraw from the ATP Finals in London with a knee injury following defeat to David Goffin, who eventually lost in the final to Grigor Dimitrov.

"Now what we want is to rest and recharge the battery after a long, hard, unbelievable year," added Moya. "Now we are not thinking much about those 1,040 points [the gap between Nadal and No 2 Federer]".

Moya also said he was shocked by Goffin's win over Roger Federer in the semi-finals in London: "It was a little bit surprising," he said. "It's the first time that he beat him and he must be given a lot of credit for beating Rafa and Federer."