The likes of Serena Williams, Novak Djokovic, Naomi Osaka and Andy Murray are on the entry list for the US Open but could still decide not to play.
And Nadal says the tournament will not be diminished if more big names opt-out.
“The tournament is still big, it’s a Grand Slam,” Nadal added.
“I am not arrogant enough to say the tournament is not big because I am not playing. There will be important players.
“Of course it’s a tournament under special circumstances but still a Grand Slam and the winner will feel like the winner of a Grand Slam. It’s true it will be under special circumstances with a lot of important players not travelling there.