Novak Djokovic claims he would have quit tennis if he doubted his ability to return to the pinnacle of the sport.

The 12-time grand slam singles champion recently re-appointed coach Marian Vajda after splitting with Andre Agassi and Radek Stepanek ahead of the Monte Carlo Masters.

Djokovic had looked a shadow of his former self during defeats to Taro Daniel and Benoit Paire in Indian Wells and Miami respectively following his return from elbow surgery.

However, the former world number one has put in promising performances to progress to the third round in Monaco and firmly believes he can hit top form once more.

"I wouldn't be sitting here in front of [the media] and competing in this tournament if I didn't believe that I can [win grand slam events and return to world number one]," said Djokovic.

"Being in that position already and having achieved so much just gives me enough reason to believe I can make it again."

"I just hope that I'll be healthy. That's the most important thing."

"I know when I'm healthy, when I'm not dealing with any significant injury that can disturb me on the way to compete and train, then I can really reach that desired level."

Djokovic also revealed that he had made a change to his racquet in a bid to improve.

"[I] changed the racquet earlier this year," he added. "I made some small minor changes that actually in our world are quite significant."

"Agassi and Radek, who worked with me at the time, felt it was a good call for the big picture and for the long run. I feel more comfortable with the racquet as I go along."

"Obviously it takes a little bit of time. I think Roger [Federer] some years ago also had that racquet change, and it took him a little bit, some months, to get comfortable with it."