Nick Kyrgios battled back from a set down to save three match points and beat Rafael Nadal in more than three hours of dramatic action at the Mexico Open.
The Australian, who has dropped to 72nd in the world rankings, also overcame a bout of nausea and a stiff back on the way to stunning Nadal 3-6 7-6 (7-2) 7-6 (8-6) to reach the last eight in Acapulco on Wednesday.
Top seed Nadal, twice a champion at the event, took only one of his 10 break-point chances and failed to put the match away despite leading 6-3 in the final set tiebreak, before Kyrgios reeled off five straight points to seal the victory in front of a lively crowd.
Nadal suffered defeat in his first tournament since the Australian Open final defeat to Novak Djokovic
After dropping the first set, Kyrgios called for the trainer and said that he felt sick, but would play on as he feared the media would "blow it up".
He returned to the court for the second set and immediately looked a different player, revelling in the atmosphere that caused a frustrated Nadal to call for the crowd to quieten down.
That request received backing from Kyrgios, who screamed "shut up" together with an expletive that brought him a subsequent warning from the umpire.
Kyrgios' match was filled with the usual drama
After calling for the trainer again between the second and third sets due to a sore back, Kyrgios then saved five break points in the sixth game of the final set.
He got out of jail again in the deciding tiebreak, particularly on the second match point when his volley caught the tape but toppled over and landed on the line.
Kyrgios will next face Swiss star Stan Wawrinka, who continued his return to form this season with a straight-sets win over American Steve Johnson, while Mackenzie McDonald fared better in the battle of his fellow countrymen by defeating Frances Tiafoe in straight sets.