Rafael Nadal's uncle and coach Toni Nadal has backed the Spaniard to end his 18-month wait for a grand slam title by triumphing at the Australian Open.

Nadal has not added to his 14 grand slam singles crowns since the 2014 French Open as injury and poor form have affected his chances against the likes of Novak Djokovic, Stan Wawrinka and Andy Murray.

Success in Melbourne has not come too often for the 29-year-old even when fit and in good form, with only one victory, in 2009, from his three final appearances.

After a strong end to 2015, Toni Nadal believes his nephew is ready to get back to challenging for the big prizes on the ATP tour, and sees no reason why that process cannot begin next month.

"I couldn't do this work if I thought that he couldn't win more grand slams," he told ESPN.

"He can win the Australian Open in January, and he can win Wimbledon, too. The last few years, Rafael arrives at Wimbledon and he loses early, and very fast. In Roland Garros, for sure, Rafael can win. 

"In tennis, you need confidence to do things. It's impossible to do anything without confidence. You can't win any good tournaments if you think you cannot and you don't believe.

"Rafael is much more comfortable on the court now."