Cape Town - When he was going through his severe dip in form, many started to doubt Novak Djokovic's ability to bounce back, but Rafael Nadal was never one of them.

As the duo prepare to battle it out for the world No 1 spot at this week's Paris Masters, Nadal said he was "not surprised at all" that Djokovic is on the verge of returning to the top of the world rankings.

While Nadal has missed nearly two months of action after retiring at the US Open with a knee problem, Djokovic has been going from strength to strength, and enters this week's event in Paris on the back of an 18-match winning streak and victories at Wimbledon, Cincinnati Masters and the US Open.

Is any of this a surprise to Nadal? Not a chance.

"I am not surprised at all - he is so good," the Spaniard told the ATP website.

By the same token, Nadal also said his own injury troubles have been acted as a contributing factor in Djokovic's climb up the world rankings.

"At the same time I played only nine events and got injured in two of them - both have been at Grand Slams," he said.

"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."

Not being quite 100% yet, Nadal knows his World No 1 ranking is very much up for grabs in Paris this week, but insists defending it is not his main source of motivation.

"I got injured in an important part of the season twice," he added. "At the beginning of the season I missed two Masters 1000 (after Australian Open injury). I then got injured at the US Open so I missed Beijing, Shanghai.

"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.

"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."