Australian maverick Nick Kyrgios sent defending champion Daniil Medvedev crashing out of the US Open in an explosive last-16 clash on Sunday and revealed he is motivated by "not letting people down".
Wimbledon runner-up Kyrgios triumphed 7-6 (13/11), 3-6, 6-3, 6-2 to reach his first quarter-final in New York where he will face another Russian, Karen Khachanov.
Kyrgios fired 21 aces and a total of 53 winners past his Russian opponent who will now lose his world number one ranking as a consequence of his defeat.
The 27-year-old crowd-pleaser has endured a tumultuous career ever since he exploded into the scene at Wimbledon in 2014.
It was there that as a teenager, ranked at 144 in the world, he shocked Rafael Nadal.
Ever since, however, Kyrgios has been better known for his controversial on-court behaviour, run-ins with officials and thousands of dollars in fines.
"I was just really sick of letting people down," said Kyrgios as he explained a rejuvenation in his career which saw him reach the Wimbledon final in July.
He took a set off Novak Djokovic before the Serb star raced away to a seventh title at the All England Club.
"I feel like I'm making people proud now. I feel like there's not as much negative things being said about me. I just wanted to turn the narrative around.
"I just was feeling so depressed all the time, so feeling sorry for myself. I just wanted to change that."
Now he is determined to keep his renaissance on track when he faces Khachanov on the Arthur Ashe Stadium in Tuesday's quarter-finals.
The last time he met the Russian, he came through in five sets in the third round of the 2020 Australian Open.
- 'Look like an idiot' -
Kyrgios had never got past the third round in New York before this year, describing his form as "really average".
"I hadn't won a match on Ashe before this week. I feel like I've been able to showcase. There's a lot of celebrities here, a lot of important people here watching," he said.
"I wanted to get on that court and show them I am able to put my head down and play and win these big matches.
"For the tennis world I think it's important as well. People were really starting to doubt my ability to pull out matches like this at majors."
In a fast-paced, big-hitting first set on Sunday, Kyrgios broke to lead 4-2 before Medvedev immediately repaired the damage.
A marathon tiebreak saw a 22-shot rally and Kyrgios save three set points.
The Australian clinched the opener on a fourth set point of his own after 63 minutes of tennis played at breakneck speed.
A furious Medvedev added spice to the encounter by complaining to umpire Eva Asderaki-Moore about the noise from the Kyrgios player box when he was serving from their end.
At the changeover, the Russian even threatened to refuse to play on if the disruptions continued.
Kyrgios left the court for a bathroom break but when he returned, his high-energy level dropped dramatically and Medvedev swept to a 5-1 second set lead on his way to levelling the contest.
Kyrgios then made the baffling decision to come around to Medvedev's side of the net to finish a point in the second game of the third set.
His illegal manoeuvre cost him what would have been a break point.
"I'm going to look like an idiot," said the Australian after the match.
However, he quickly broke the equally baffled Russian for a key 3-1 lead before pocketing the third set.
A fired-up Kyrgios broke for 2-1 in the fourth set, was handed a code violation for swearing and responded with back-to-back aces timed at 122mph and 131mph to stretch to 3-1.
He backed it up with another break for 4-1 as Medvedev wilted under the barrage before Kyrgios sent down his 21st ace to seal victory.