Rafael Nadal will return to the ATP Tour after an injury-enforced three-month absence at the Monte-Carlo Masters, but coach Carlos Moya says he is struggling for confidence.

The hip problem that forced the world number one to retire from his Australian Open quarter-final against Marin Cilic in January put him out of commission until Spain's Davis Cup quarter-final win over Germany last week.

Nadal was in stunning form on clay - his favoured surface - in 2017, phenomenally winning 10th titles at Monte Carlo, Barcelona and the French Open.

But, unlike last year, Nadal sat out the ATP Masters 1000 events in Indian Wells and Miami this season and seemingly does not have the same mentality he possessed in the early stages of his surge back to the top of the world rankings.

"Rafa has been more inactive, with fewer games than last year and a little less confidence because he is the type of player who thinks he has to play a lot of games to get right for the big moment," Moya is quoted as saying by AS.

"I believe a tennis player of his quality depends less on that and more on being without physical issues. It looks positive and if he doesn't have a physical problem he will have a great season."

That need to build confidence through competition opposes Moya's thoughts on how Nadal should be managing his playing time at this stage of his career.

The coach said: "He wants to play in everything, to always be available. But he is realising that he is getting older and the kilometres and matches are piling up. He can see it. I, as a player, was also like that. Now I'm not, and I have to make him see that it can be worthwhile to not play so much and extend [his career] a little more."

"He is doing well, but what he does not take well are the injuries, which hurt more than the defeats."