Nadal, who has never won the Paris Masters, did not know yet whether he would be fit for London. "I did one treatment yesterday night to try and play today".
The 31-year-old Nadal became the oldest player to top the rankings in its 44-year history.
He added: "Of course it [withdrawal from Paris Masters] is a very tough decision for me, especially here in Paris, which has been the most important city in my career without a doubt".
The pain during the match was too much.
"I have to pull out".
"It's not about London, it's about the longer term", he explained.
He further said, "I'm going to do my treatment, do my best to be playing in London, but I can not talk about that now because (it) is a day that is tough enough for me to pull out from here".
Juan Martin del Potro missed out on securing the final qualifying spot for the ATP World Tour Finals as he was beaten 6-4 6-7 (5-7) 6-4 by John Isner.
Nadal started this season ranked No. 9 in the world, but a resurgent year-in which he has won the French Open and the U.S. Open and reached the Australian Open final-will see him end 2017 as the world No. 1, even if he has played his last match. He's made the finals in Stockholm, semis and quarters in Shanghai and Beijing. "But I didn't want to stop", Nadal said. After all, the two legends had nothing better to do, like sweep all the major prizes in their sport, like they did this year!
Benneteau, playing in just his second Masters event of the season after being given a wildcard, let out a huge roar when he saved a break point and held to move within a game of victory in the second set.