Brisbane - Mercurial Australian Nick Kyrgios edged world number seven Stefanos Tsitsipas in an enthralling clash at the ATP Cup in Brisbane on Tuesday.
Both players were in superb touch but Kyrgios seized his chance in the third set tiebreak to win 7-6 (9/7), 6-7 (3/7), 7-6 (7/5) in just over two and a half hours on Pat Rafter Arena.
Kyrgios's win gave Australia an unassailable 2-0 lead in the tie following John Millman's win over Michail Pervolarakis, and ensured the home side finished the round robin segment of the ATP Cup with a perfect record.
"I knew it was going to be a very tough match - we've played once before and it was 7-6 in the third," Kyrgios said.
"He's an amazing player and he's so young. I'm just glad we got the win."
The 24-year-old has often divided fans because of his poor behaviour on court, but he was the model of sportsmanship against Tsitsipas.
Instead it was the Greek star who was in trouble with the umpire after he smashed his racket, accidentally hitting his father's arm in the process, and then hit a ball towards the Greek coaching staff in frustration.
Both men served superbly throughout - Kyrgios sent down 25 aces and Tsitsipas 18 - and only faced three break points between them, all of them saved.
But it was the dynamic Kyrgios, playing with power and incredible touch, who prevailed in front of a raucous home crowd.
Earlier, Millman dug deep to avoid the upset of the tournament against world number 487 Pervolarakis.
The little-known Greek, who had never played on the main ATP tour before this week, pushed Millman all the way before the Brisbane local won 4-6, 6-1, 7-6 (7/1).
In the first tie of the day Alexander Zverev's terrible run of form showed no signs of abating after the German surrendered meekly to Canada's Denis Shapovalov 6-2, 6-2.
Canada won the tie in Brisbane 2-1 to keep alive their hopes of reaching the inaugural event's quarter-finals after Shapovalov teamed with Felix Auger-Aliassime to win the deciding doubles rubber.
The pair edged Kevin Krawietz and Andreas Mies 6-3, 7-6 (7/4) in a high quality match.
Shapovalov cruised to his win in just 70 minutes to level the tie after Jan-Lennard Struff had earlier got Germany away to a winning start with a 6-1, 6-4 win over Auger-Aliassime.
It was Zverev's third straight loss at the ATP Cup.
He fell to Australian Alex de Minaur in three sets in the first round before suffering a comprehensive 6-1, 6-4 loss to Greece's Stefanos Tsitsipas on Sunday.
The world number seven conceded he had major problems ahead of the first Grand Slam of the year.
"Generally I'm not playing good, so there's a lot of things that I still need to improve, but it's the start of the season," Zverev said.
"The first match I actually thought I played okay - the serving was horrible - but then I played two very bad matches, but what can I do?"