Rafael Nadal was disappointed to miss the Swiss Indoors
Nadal pulled out of the event citing a knee injury after a busy schedule of matches over the autumn.
In his absence, Roger Federer swept to victory at his hometown tournament, beating Juan Martin del Porto in three sets in the final.
But the situation has been flipped at this week’s Paris Masters with Federer withdrawing from the tournament.
While Nadal will make his return to the ATP tour this week knowing that he needs just one win to seal the year-end number one position.
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I was sad not to play in Basel
But speaking ahead of his match with South Korea's Hyeon Chung, Nadal expressed his disappointment at having to miss Basel.
He said: “I was sad not to play in Basel. It’s always been a tournament that always supported me.
“Very tough decision but at the same time it was a mandatory decision for me. No chance to keep playing. Too many matches.
"[My] body always needs some rest at this part of the season and that’s the decision I took. That’s all.
“I arrived Friday [in Paris]. I think I’m practising well. I hope to be ready for the action.”
Roger Federer won the Swiss Indoors on Sunday
Tournament director of the Paris Masters, Guy Forget, has criticised Federer over his decision to skip the event.
Speaking to L'Equipe, Forget said: "You imagine my disappointment, my frustration (at Federer's withdrawal). I had his agent (Tony Godsick) on the phone who told me of his wish to recover because he is at the end of the roll. We take note of it.
"We have no other recourse against that. We are sad about all the efforts that have been made for many weeks and many months to welcome Roger and Rafa into this room.
"Unfortunately, Rafa will be alone. There are other great champions, but I am convinced that Roger's Parisian fans will be very disappointed."