Nadal has yet to be troubled during the start of his US Open campaign with comfortable wins against David Ferrer and Vasek Pospisil.
But NextGen star Khachanov brings a completely different challenge within itself and the world No 1 is wary of avoiding a shock defeat.
However, like always, the Spaniard will not be too fussed about his opponent as long as he focusses on his own game.
“He is a powerful player. He is young and he has everything,“ Nadal told ESPN while on his way to the Arthur Ashe Stadium.
“He has a good serve and shots from the baseline. I need to be aggressive and I need to play well. That’s the most important thing.
“I need to play my game and do it well.”
Nadal’s clash with Khachanov will be his first day match of the tournament – but that has not changed his preparations too much.
“We get used to that, it is not a big deal,” Nadal added.
“We just had to adjust the timings a little bit this morning.
“I have had the right warm-up but we are ready for the match.”
Meanwhile, Khachanov acknowledged he faces a big ask if he is to pull off a huge upset.
“First off I have played the opening two matches really consistent. I haven’t lost my serve and I have played really solid,” he added.
“I am looking forward to playing against the world No 1 Rafa.
“I think I have to play like always. I don’t have to change my game.
“I have to play aggressive and keep pushing on my serve and on his serve.”