Rafael Nadal is confident that injury will not prevent him from putting on a show at the ATP Finals in London as he seeks his first title at the tournament.

The world number one is scheduled to begin his campaign against David Goffin on Monday, but suffered a fitness scare when a right knee problem forced his withdrawal from last week's Paris Masters.

However, the 16-time grand slam champion is adamant that he is ready for the gruelling demands of the star-studded season-ending event.

"If I didn't believe I could be ready for Monday I wouldn't be here," he said on Friday.

"I don't have to make a decision. I'm going to play. That's my feeling today.

"I had problems in Paris a week ago. I go day by day, how I'm feeling.

"I cannot predict what will happen, but my feeling now is I'm going to play and try my best."

As top seed, Nadal will be the man everyone is out to beat, including long-time rival Roger Federer.

While the Swiss has won the title six times, Nadal has yet to taste glory, losing in the 2010 final to Federer and coming up second best against Novak Djokovic in 2013.

"It's always in my mind, during 13 years that I'm qualified," added the 31-year-old, who is already assured of ending the year at the top of the rankings, an achievement that will be recognised in London.

"Being here is an important thing, but for me the most important thing is the only thing that happened to me this year. Winning tournaments, competing every week, being healthy until Paris.

"I'm number one here, great. It's a very important achievement, especially at my age.

"It's something important for me, but that's all. It's going to be a nice moment when I receive Sunday the award, a year ago it was never in my mind to achieve that again.

"For me the most important thing is to finish the season well."

Reigning champion Andy Murray and five-time winner Djokovic are absent after injury plagued seasons, while Federer kicks things off against Jack Sock on Sunday.