Melbourne - Showman Nick Kyrgios admitted on Thursday he was on the verge of going "to a very dark place", but he put his head down to pull off a confidence-boosting win over Frenchman Gilles Simon at the Australian Open.
The 24-year-old had the measure of the veteran early on then lost concentration and became agitated before refocusing to win 6-2, 6-4, 4-6, 7-5 on his favoured Melbourne Arena.
It set up a third-round clash with Russian 16th seed Karen Khachanov who beat Sweden's Mikael Ymer in five sets, with the winner on course to meet world No 1 Rafael Nadal in round four.
"I definitely lost my way a little bit... but I decided to refocus," Kyrgios said of his mini-meltdown in the third set. "I could have gone to a very dark place in the fourth set.
"I put my head down, I told myself, 'Just cut the bull***t and just get to work'. I got the break at 5-all. It was a good feeling to get through that."
And in a sign of a new-found maturity, he apologised to his player box after admonishing them when he was under pressure in the third set.
"I apologised as soon as I went back into the locker room. They don't deserve that," he said.
"They do a lot of things for me on and off the court. No, it's not acceptable from me. Nothing to do with them."
Kyrgios has spoken of how the bushfire crisis in his homeland has given him perspective and focus, and that he felt he was playing for the nation rather than just himself.
And with the roars of the crowd ringing in his ears, he broke the Frenchman in the first game and consolidated by holding serve.
Kyrgios looked sharp and broke again for 5-2 then served out the set, sending down five aces and, crucially, making only two unforced errors.
Simon was struggling with his serve and the Australian broke again for a 1-0 lead in the second set, making some big shots when it counted.
It went with serve before Kyrgios, watched again by his ATP Cup captain Lleyton Hewitt, won the set with another rocket serve.
He broke Simon again early in the third set, letting out a huge "C'mon!"
But the Frenchman broke back as Kyrgios started to lose concentration in game eight, berating himself and gesturing to his box as frustrations kicked in.
He lost the set as his focus drifted and he yelled at his box: "Of all the things you could say, 'Stay tough'. Thanks man, thanks. That's what I get, every break point, 'Stay tough'. Wow."
But the Australian conquered his mental demons to regroup, getting a crucial break to go 6-5 up in the fourth and completing victory with a big ace, his 28th of the match.
"I feel good physically. That's probably the positive I take out of today," said Kyrgios.
"Long rallies, long match... I feel fine at the moment."
Results on day four of the Australian Open Grand Slam at Melbourne Park on Thursday (x denotes seeding):
Rafael Nadal (ESP x1) bt Federico Del Bonis (ARG) 6-3, 7-6 (7/4), 6-1
Pablo Carreno-Busta (ESP x27) bt Peter Gojowczyk (GER) 6-4, 6-1, 1-6, 6-4
Nick Kyrgios (AUS x23) bt Gilles Simon (FRA) 6-2, 6-4, 4-6, 7-5
Karen Khachanov (RUS x16) bt Mikael Ymer (SWE) 6-2, 2-6, 6-4, 3-6, 7-6 (10/8)
Gael Monfils (FRA x10) bt Ivo Karlovic (CRO) 4-6, 7-6 (10/8), 6-4, 7-5
Ernests Gulbis (LAT) bt Aljaz Bedene (SLO) 7-5, 6-3, 6-2
Taylor Fritz (USA x29) bt Kevin Anderson (RSA) 4-6, 6-7 (5/7), 7-6 (7/4), 6-2, 6-2
Dominic Thiem (AUT x5) bt Alex Bolt (AUS) 6-2, 5-7, 6-7 (5/7), 6-1, 6-2
Daniil Medvedev (RUS x4) bt Pedro Martinez (ESP) 7-5, 6-1, 6-3
Alexei Popyrin (AUS) bt Jaume Munar (ESP) 6-2, 7-6 (7/5), 6-2
John Isner (USA x19) bt Alejandro Tabilo (CHI) 6-4, 6-3, 6-3
Stan Wawrinka (SUI x15) bt Andreas Seppi (ITA) 4-6, 7-5, 6-3, 3-6, 6-4
David Goffin (BEL x11) bt Pierre-Hugues Herbert (FRA) 6-1, 6-4, 4-6, 1-6, 6-3
Andrey Rublev (RUS x17) bt Yuichi Sugita (JPN) 6-2, 6-3, 7-6 (7/5)
Fernando Verdasco (ESP) bt Nikoloz Basilashvili (GEO x26) 4-6, 7-6 (7/5), 6-4, 6-4
Alexander Zverev (GER x7) bt Egor Gerasimov (BLR) 7-6 (7/5), 6-4, 7-5
Belinda Bencic (SUI x6) bt Jelena Ostapenko (LAT) 7-5, 7-5
Anett Kontaveit (EST x28) bt Sara Sorribes (ESP) 6-2, 4-6, 6-1
Donna Vekic (CRO x19) bt Alize Cornet (FRA) 6-4, 6-2
Iga Swiatek (POL) bt Carla Suarez (ESP) 6-3, 7-5
Elise Mertens (BEL x16) bt Heather Watson (GBR) 6-3, 6-0
Catherine Bellis (USA) bt Karolina Muchova (CZE x20) 6-4, 6-4
Yulia Putintseva (KAZ) bt Danielle Collins (USA x26) 6-4, 2-6, 7-5
Simona Halep (ROU x4) bt Harriet Dart (GBR) 6-2, 6-4
Garbine Muguruza (ESP) bt Ajla Tomljanovic (AUS) 6-3, 3-6, 6-3
Zarina Diyas (KAZ) bt Anna Blinkova (RUS) 4-6, 6-3, 6-4
Kiki Bertens (NED x9) bt Arina Rodionova (AUS) 6-3, 7-5
Camila Giorgi (ITA) bt Svetlana Kuznetsova (RUS) 6-3, 6-1
Angelique Kerber (GER x17) bt Priscilla Hon (AUS) 6-3, 6-2
Anastasia Pavlyuchenkova (RUS x30) bt Taylor Townsend (USA) 7-5, 7-6 (7/1)
Karolina Pliskova (CZE x2) bt Laura Siegemund (GER) 6-3, 6-3