They are set to battle for year-ending world number one title at the ongoing Pairs Masters and at ATP Tour finals later this month, but Rafael Nadal has said he is happy arch-rival Novak Djokovic is back to playing his best tennis.

Nadal maintained he never doubted a comeback from the Serb, who seems to have hit peak form after a prolonged struggle with elbow issues over the last two seasons.

"I am not surprised at all - he [Djokovic] is so good. At the same time I played only nine events and got injured in two of them - both have been at Grand Slams," Nadal told ATP's official website.

"He is having a great second part of the season so he deserves to be where he is. Everybody was sure he would be back to his best and I am happy to see someone like him back playing at that high level."

Djokovic had struggled with multiple injury and motivational issues in 2017 wherein he failed to win a Grand Slam title for the first time after six years.

The 13-time Grand Slam champion was visibly frustrated during the first half of the season as his early comeback from injury didn't go as planned. He even conceded he was unsure about returning to his dominant best after an early exit from Monte Carlo Masters.

Nonetheless, Djokovic turned it around and found success at Wimbledon, which was his first major title since the French Open victory in 2016.

Djokovic, who seems to have reinvented the hunger, has managed to maintain the new-found consistency with titles at US Open and Shanghai Masters.

Rafael Nadal
French Open - Roland Garros, Paris, France - June 10, 2018 Spain's Rafael Nadal celebrates with the trophy after winning the final against Austria's Dominic Thiem. Reuters

The 31-year-old has put himself in a position where he can leapfrog Nadal and finish the year as the top-ranked men's singles player. Djokovic is only 215 points behind the Spaniard, who will also drop 180 points as he had reached the Paris Masters quarter-final last year.

Considering his form, Djokovic is the overwhelming favourite to finish the year on top of the charts.

'The main goal is to be back on court'

On the other hand, Nadal, who returns to the tour for the first time since retiring in the US Open semi-final with a knee injury, isn't too concerned about the race for the top spot. The 17-time Grand Slam champion instead wants to focus on getting game time.

"So, too many tournaments lost. My main goal is to be back on court, to be happy playing tennis and keeping healthy. Then with things that can happen or not... let's see," Nadal said.

He added: "I am going to fight as strong as I can to win as many matches as possible. Of course, I would love to [remain] No 1 but I am here to just try my best every day."