NICK Kyrgios has overcome a searing challenge from Croat veteran Ivo Karlovic to reach the Miami Open's fourth round.
Taken to the brink, Kyrgios prevailed 6-4 6-7 (4-7) 7-6 (7-2) to earn a shot at either Belgian David Goffin or Argentine Diego Schwartzmann.
Elated with a performance that demanded mental resilience as much as physical endurance, Kyrgios handed his towel and wristbands to a ball boy at the end of a sapping contest.
The Australian had been jeered after throwing his racquet, but was applauded warmly after toppling ageless Karlovic.
While Kyrgios was out-aced 14-16 by the remarkable Karlovic, the Canberran lost just four points on his first serve for the match.
Kyrgios was clearly superior on return but was repeatedly foiled by Karlovic, who successfully defended eight of nine break points - most of them late in the second set.
The match turned on a Karlovic double fault in the decisive tiebreak.
From there, Kyrgios clinically sealed a confidence-boosting victory ahead of Australia's Davis Cup clash with the US in Brisbane next week.