"The first set and a half I think was [at] a great, great level. I am very happy with the way I played," Nadal said as he came off court.
The 30th-seeded Khachanov was more blunt: "He started really fast. He was destroying me."
The 21-year-old Russian regrouped in the second set as Nadal's level dipped from ferocious to merely fearsome. He stopped the slide after Nadal broke in the third game by booming down four aces to hold in the fifth.
Khachanov reached a set point in the third, but Nadal was too strong and too accurate to let him back into the match and ruin his straight-sets run.
Nadal, 31, won this year's French Open, his 10th title at Roland Garros, without dropping a set. He has kept up that pace at Wimbledon as he aims to convert his red-hot clay form and claim a first grasscourt slam title since 2010.
With yesterday's win, he has now bagged 28 consecutive sets at the grand slams this year, laying down a marker to his rivals in his quest for a 16th major title.
Nadal next faces a grass specialist in Luxembourg's Gilles Muller, seeded 16, in the fourth round on Tuesday.
Andy Murray survived a scare but eventually overcame volatile Italian Fabio Fognini in four sets with a dramatic surge to dig himself out of trouble.
The British defending champion triumphed 6-2, 4-6, 6-1, 7-5 on Centre Court, winning five consecutive games in the fourth set and saving five set points to book himself a spot in the fourth round. Murray struggled to find his rhythm throughout the match or read what was his third unpredictable opponent in a row after Alexander Bublik and Dustin Brown.
The world No1 faces France's unseeded Benoit Paire on Tuesday for a place in the quarter-finals.
"I served it out really well to finish. But it was an up and down match. I didn't feel like it was the best tennis at times. It was a little bit tense but I managed to get through," Murray said. "It's obviously difficult when you're playing a guy who has all of the shots like him. He generates power with very short swings. It's difficult to see when he's going to hit the ball big. He was taking me out of my rhythm.
"It was also getting dark towards the end. We would probably had to have come off and closed the roof had I lost that fourth set so you're thinking a little bit about that as well, a change of conditions and a 20-minute break to think about things before playing a fifth set. So obviously pleased to get off in four."
In the women's draw, five-time champion Venus Williams battled through to the fourth round with victory over Japan's Naomi Osaka.
The 37-year-old, who won her first SW19 crown in 2000, overcame her powerful teenage opponent 7-6(3), 6-4 on Court One.
- AAP
