Australia's Nick Kyrgios survived three match points to beat top-seeded Rafael Nadal 3-6, 7-6 (7/2), 7-6 (8/6) on Wednesday and reach the quarterfinals of the Mexico Open.
It was a bravura finish to a drama-filled match in which Nadal, playing his first tournament since falling to Novak Djokovic in the Australian Open final, had three chances to close it out after taking a 6-3 lead in the third-set tiebreaker.
Kyrgios saved the first with a leaping drop shot, and the second with a net-skimming volley.
Nadal was just wide with a passing shot to make it 6-6, double-faulted to give Kyrgios a chance and sailed a backhand long to end the match after three hours and three minutes.
Kyrgios screamed and dropped to the court in celebration -- a conclusion that seemed unlikely when he complained to a trainer after the opening set that he was feeling ill but feared the fallout should he retire.
Kyrgios steeled himself to continue, and distractions seemed forgotten as he became absorbed in the battle against the 17-time Grand Slam champion.
Down 0-40 in the ninth game of the second set, Kyrgios saved four break points to keep the set on serve and raced to a 5-0 lead in the tiebreaker.
Kyrgios, who received treatment on his lower back before the start of the third, was in trouble again in the sixth game but fought off five break points to stay on terms and push it to the decisive tiebreaker.
Kyrgios leveled his head-to-head record with Nadal at 3-3 and will play three-time Grand Slam champion Stan Wawrinka for a place in the semifinals.
Switzerland's Wawrinka, seeded third, belted 32 winners in a 7-6 (7/5), 6-4 victory over American Steve Johnson.
Women's top seed Sloane Stephens also bowed out Wednesday, stunned by Brazilian qualifier Beatriz Haddad Maia 6-3, 6-3.
Haddad Maia, 22, next faces China's Want Yafan, who was leading Monica Puig 4-1 when the Puerto Rican retired with an injury.
Former world number one Victoria Azarenka of Belarus sailed into the quarter-finals, downing Tatjana Maria 6-2, 6-1.
Azarenka fired 20 winners to Maria's 10, and took full advantage of the German's 28 unforced errors.