SYDNEY (Reuters) - Australian Nick Kyrgios outlasted world number six Stefanos Tsitsipas 7-6(7) 6-7(3) 7-6(5) after an intense duel to seal the tie for the hosts against Greece at the inaugural ATP Cup team event in Brisbane on Tuesday.
Kyrgios slammed a backhand winner on matchpoint and fell on his back to celebrate his second win in as many meetings against the ATP Finals champion as the partisan crowd at the Pat Rafter Arena roared on.
His win ensured Australia will go to the knockouts having won all their ties in the $15 million ATP Cup, which features 24 nations competing in Perth, Brisbane and Sydney over 10 days.
"Exhausting! It was lot of fun. Knew it was going to be a tough match," Kyrgios said in a courtside interview. "He's an amazing player and he's so young. He's going to do some special things in the sport."
Kyrgios had missed the tie against Canada with a back problem and on Tuesday replaced Australia number one Alex de Minaur, who sat out with an abdominal strain.
While Kyrgios, who has been placed on probation by the governing body of men's tennis over his behaviour, losing his cool on court is not surprising, it was Tsitsipas who was docked a point for hitting a ball at the Greek Team Zone.
The 21-year-old also broke his racquet in frustration after losing the opening set which earned him a berating from his mother, who was present in the team zone.
Kyrgios stayed unfazed and kept his focus on his own game, which consisted of his usual through-the-leg tweeners, no-look drop shots and one underarm serve.
"I am on probation, so I got to stay in check. I'm trying, I'm trying (to be a good boy)," he said as the crowd clapped in appreciation.
Canadian Denis Shapovalov earlier picked up his second win against a top-10 player with a 6-2 6-2 thumping of Alexander Zverev as the German continued to struggle with his serve ahead of this month's Australian Open.
Shapovalov, 20, needed just 70 minutes to brush aside world number seven Zverev, who lost his third straight singles before the year's first Grand Slam starting in Melbourne on Jan. 20.
Zverev, the 2018 ATP Finals champion, served seven double faults against Shapovalov to take his total for the tournament to 31.
"There's a lot of things that I still need to improve, but it's the start of the season," Zverev said. "I need to find my rhythm."
Shapovalov, who beat Tsitsipas in his opening match, returned with team mate Felix Auger-Aliassime to win the deciding doubles rubber against Kevin Krawietz and Andreas Mies 6-3 7-6(4), earning Canada a 2-1 win in the tie to keep them in the hunt for the quarter-finals.
All six group winners and the two best second-placed teams will advance to the final eight in Sydney. Besides the hosts, Serbia, Britain and Russia have already qualified.
Russian Daniil Medvedev, the U.S. Open finalist and world number five, won his third straight singles rubber in Perth, beating Norway's Casper Ruud 6-3 7-6(6).
(Reporting by Sudipto Ganguly; editing by Ed Osmond and Christian Radnedge)