World reacts to Kyrgios’ Australian Open epic

Nick Kyrgios had to dig into his deepest reserves on Saturday night to prevail in a five-set marathon that smashed the record for his longest ever career match.

Up 4-2 in the third with a two-set lead, Kyrgios appeared to be cruising towards a straight sets win over Russian 16th seed Karen Khachanov.

But then he opened the door, and it nearly slammed right back in his face.

Kyrgios looked fatigued, frustrated and carried a few niggles through back-to-back tie breaks that went the way of his Russian rival in the third and fourth sets.

The two then traded blow for blow in the fifth, both showing great endurance and firepower, but it was Kyrgios who prevailed.

"This is the best effort he has ever given on a tennis court," tennis legend John McEnroe said on commentary for ESPN.

"This is the deepest he has ever dug."

The tennis world was left sitting on the edge of their seats as the enthralling duel played out, here's how they reacted.

Kyrgios led the match tiebreak 3-0 before losing four straight points. He then was broken at 7-7, but won three consecutive points to claim the match.

It was the longest match in Kyrgios' career, lasting four hours and 26 minutes, surpassing his 2014 Wimbledon meeting with Richard Gasquet.

The win now sets up a thrilling fourth round matchup against World No.1 Rafael Nadal who Kyrgios has had a long-simmering feud with.

Unfortunately for his strong contingent of fans the match won't be played on his favoured Melbourne Arena, instead it will take place on the main stage of Rod Laver Arena.