Nadal, 31, cut a buoyant figure this morning as he warmed up at the O2 ahead of the ATP World Tour finals.
There have been serious fears Nadal may have to pull out the event with a right knee injury.
But he appeared to be in good spirits as he went through his paces without any strapping on the knee.
It is the biggest suggestion yet that Nadal is likely win his fitness race and will be battling it out to take the tournament for the first time.
Nadal has already sealed the world No 1 spot but he has a point to prove against Roger Federer, who has won the last five meetings between the pair.
The Spaniard yesterday said he is confident he will be “100 per cent fit”.
That’s despite pulling out of the Paris Masters before his quarter-final match after experiencing discomfort in his right knee during his third-round win over Pablo Cuevas.
“Hopefully the knee is good,” Nadal told Sky Sports. “I’ve done everything I’ve needed to do in order to get ready for London.
Now it’s the moment to wait and practice at the O2 over the next couple of days. Let’s see if I am able to be 100 per cent to compete.
“If nothing happens, then I will play. I visited my doctors after the Paris Masters – it was a tough day for me having to pull out of Paris. Pulling out of any tournament in the world is tough, but pulling out of the city of Paris is especially tough for me.
“That’s how it is. I went back home and visited the doctors to do some treatment. I expect the treatment to work and be ready for here.
“I know I’m confident because I’m having a great season with one event to go. I am here to try my best.”
Nadal begins the quest for his first ATP Finals title against Belgian David Goffin on Monday.
He will also compete with Bulgarian Grigor Dimitrov and Austrian Dominic Thiem in his group.