TENNIS:Nadal eye four to five Grand Slam titles

The way he looks right now, Rafa Nadal could add at least four or five more Grand Slam titles" - Leif Shiras says the world No 1 is looking unplayable.

Nadal's victory over Stan Wawrinka in the final of the French Open in June ended a three-year wait for his 15th Grand Slam title, overcoming injuries and a loss of confidence in his body and his game.

And after the Spaniard pummelled Kevin Anderson into submission in the final of the US Open to edge closer to Roger Federer's tally of 19, Sky Sports analyst Shiras believes the 31-year-old is looking like an unstoppable force once again.

"Nadal is playing maybe the best of his life - you could almost say that. He has benefited historically from one of his most favourable draws at the US Open. I don't think Rafa normally gets draws this favourable but he took full advantage of it," said Shiras.

"We all knew Nadal was so effective at the net but some people are whispering to me that he could be an even better volleyer than Roger Federer.

"That's a debate for another time, but fact that he's doing so well when he comes forward shows signs that if he can end points earlier and be tactically layered like he is in terms of his defensive play, the sky's the limit for Rafa.

"The way he looks right now, Rafa could add at least four or five more Grand Slam titles, so he has a very good chance to catch and surpass Roger just because of how he looks physically."

When the 31-year-old heads to Australia in January he will be accompanied by coaches Francisco Roig and Carlos Moya, who takes over the lead role from Uncle Toni.

Former French Open champion Moya was Majorca's first world No 1and a long-time friend of the family.

This season has seen Moya help Nadal rediscover his best form and reach three Grand Slam finals, winning two of them.

"Carlos Moya has done an amazing job," said Shiras. "The one thing that he has done other than rediscover Rafa's passion is that he's got him to take the ball early on the backhand side and drive it crosscourt. He's always going to be able to defend, so he can always fall back into that mode and defeat 80 per cent of the guys just doing that.

"When's he's taking the ball on the backhand side that's going to open up a world of hurt on the forehand. The guy deals with adversity so well. When he loses a point you don't see any difference in the reaction to when he wins a major title. He just gets out of there and competes."

Nadal began this season ranked No 9, having pulled out after the second round of the French Open and skipped Wimbledon entirely because of an injured left wrist. Federer was No 16, having missed the final half of 2016 due to a knee injury.

"It's been an amazing story with Roger and Rafa splitting the four Grand Slams. The last time that happened was in 2010. Here they are both in their 30's pulling off the same feat - it's remarkable," admitted former world No 31, Shiras.

"Roger will have to manage his schedule moving forward and the ability to get the best out of an older body.

"Roger will probably peel back his schedule to the bare minimum so that he can have a good strong finish. Rafa might play one or two more events but it looks like Rafa will end the year as world No 1 unless something dramatic happens."