Nadal will go up against his old rival in the Indian Wells Masters semi-final later today (play is expected to start around 19:20).
The Spaniard got past Karen Khachanov in the quarter-finals 7-6 7-6, but was left contemplating cause and effect and painful knee tendinitis flared up.
Nadal has said he has no idea whether or not he will be fit to face Roger Federer, aside from being “hopeful”.
And the 32-year-old, who has battled a series of knee injuries, insists that while he loves hard court tennis it is not great for the players involved.
When asked if he thought playing on hard courts contributed to his injury history, he replied: “Probably it’s more than 1,100 matches on tour, more than any surface.
“I love to play on hard, but probably my body don’t love it that much.
“And my feeling is there are a lot of players that love to play on hard, true, but their bodies don’t love to play on hard, either.”
Rafael Nadal has won the French Open – played on clay – a record 11 times – but of his 17 Grand Slam victories only two have come on the Wimbledon grass.
“It’s not about only during the tennis careers that I am worried,” he added.
“When I see some old legends walking around the tour, it’s tough.”
Nadal insists he will do his best to recover in time to face Federer, saying: “I will try my best to recover – these are the matches I want to play.
“To play against my biggest rival at the later stages of our careers and to keep competing against each other is great.”
The Federer-Nadal rivalry is one of the greatest in tennis history, with the pair set for the 39th meeting of their careers.
Nadal edges the head-to-head having won 23 of the 38 encounters, with Federer triumphing on only 15 occasions.
The two greats last played each other in the final of the Shanghai Masters back in October 2017, with Federer winning in straight sets.
But the Swiss legend said: “I don’t think those matches matter that much, to be honest.
“A lot of time has gone by, unfortunately maybe for the rivalry, for us, or for me. It’s always better to keep on playing against him.
“The fans are maybe more excited about us playing than me as I’ve always got to be focused on my own game.
“But it always brings extra energy into the stadium and for the both of us.”