Indian Wells: Novak Djokovic exits at the hands of world number 123 Luca Nardi

Nardi, 20, booked a last-16 meeting with American Tommy Paul as he won 6-4 3-6 6-3.

Currently 123 in the world, the Italian is the lowest-ranked player to beat Djokovic at ATP Masters 1000 or Grand Slam level.

"I don't know [how I held my nerve]," he said. "I think it is a miracle, because I am a 20-year-old guy, 100 in the world, and beating Novak. It's crazy."

Sealing his victory with his sixth ace, Nardi hit 16 winners in the final set against just two from the five-times Indian Wells champion.

"It's fine. You know, it's part of the sport," said Djokovic. "You just have to accept it. Some you win; some you lose. Hopefully I'll win some more and still keep going.

"I guess every trophy that eventually comes my way is going to be great, obviously to break the kind of negative cycle a little bit I'm having in the last three, four tournaments where I haven't really been close to my best."

Paul reached the last 16 with a 6-4 6-4 win over France's Ugo Humbert while seventh seed Holger Rune, ninth seed Casper Ruud, Taylor Fritz and Grigor Dimitrov all moved through in straight sets.

Dimitrov will play fourth seed Daniil Medvedev, who needed three sets to beat Sebastian Korda 6-4 5-7 6-3.

But British number one Cameron Norrie went out after a dramatic 6-7 (5) 7-6 (5) 6-3 defeat to French veteran Gael Monfils.

The British number one led by a set and 3-0 before falling victim to a stirring comeback from the 37-year-old.

Monfils clawed back to level in an extraordinary second set tie-break in which he won a point with an underarm serve before clinching the set at the end of a stunning 31-stroke rally.

READ MORE: Novak Djokovic challenged in Indian Wells return, Cameron Norrie marches on