Novak Djokovic kicked off his season in style with a 7-5, 7-5 win over Canadian talent Denis Shapovalov on his favourite Rod Laver Arena court on Tuesday before returning to lead Serbia to a doubles victory that sealed their ATP Cup opener 2-1.
Leading Serbia's title defence in the team-based event, Djokovic was thrilled with his form in the Group A clash, a rematch of last year's quarter-final against Shapovalov.
"It's a great opening of the season. I hope all of you who came here enjoyed it because I certainly did," the world number one told a small crowd at the stadium, soaking up boisterous cheers from Serbian fans.
Last year the Canadian pushed Djokovic to a third-set tiebreak but the Serb wrapped things up more quickly on Tuesday, breaking Shapovalov as he served to stay in the match.
Himself unbroken on serve, Djokovic sealed the match with a sparkling winner, scrambling to his right to whip a curling forehand passing shot down the line.
The win levelled the tie at 1-1 after Canada's Milos Raonic had eased past Dusan Lajovic 6-3, 6-4.
Djokovic, who will bid for a record-extending ninth Australian Open title, returned to play in the decisive doubles with Filip Krajinovic and the pair clinched the tie with a 7-5 7-6(4) win over Raonic and Shapovalov.
While Djokovic, now unbeaten in 10 ATP Cup matches, enjoyed a dream start world number three Austrian Dominic Thiem slumped to a 6-2, 6-4 defeat to Italy's Matteo Berrettini in his opener.
Blasting groundstrokes metres past the baseline, the US Open champion was broken four times in a rusty display at John Cain Arena as Berrettini dominated the clash of hard hitters.
Thiem rallied in the second set to break Berrettini for the first time but surrendered the match the way he played it, with a big swing at a backhand that thudded into the net.
Having pushed Djokovic to five sets in the Australian Open final last year, Thiem is among the top contenders looking to dethrone the Serb at the February 8-21 Grand Slam.
Berrettini was ecstatic to take down Thiem in the Group C tie and put Italy back on level terms with Austria at 1-1 after Dennis Novak romped past Fabio Fognini 6-3, 6-2 in the morning.
"I'm really happy for my performance," Berrettini said on court.
"Playing for your country is something special."
There was more joy for Berrettini as he returned for doubles duty alongside Fognini to trounce Thiem and Novak 6-1, 6-4 and claim victory for Italy.
Last year's finalists Spain suffered a blow ahead of their Group B tie against hosts Australia when world number two Rafael Nadal pulled out with a lower back problem.
But Roberto Bautista Agut and Pablo Carreno Busta did not let Spain feel the absence of the 20-times Grand Slam winner, defeating Alex de Minaur and John Millman in their respective singles matches to settle the tie.
World number four Daniil Medvedev and eighth-ranked Andrey Rublev also won their singles matches to help Russia to victory over Argentina in Group D in the evening session.
Medvedev downed ninth-ranked Diego Schwartzman 7-5, 6-3 after Rublev stormed past Guido Pella 6-1, 6-2.
France, the other Group C team, start their tournament against Italy on Wednesday. The winning nations of the four groups advance to the semi-finals.
Nadal out of Spain's ATP Cup tie against Australia with back issue
World number two Rafael Nadal said he pulled out of Spain's opening ATP Cup tie in Melbourne with a lower back problem with less than a week left for the Australian Open.
Nadal was due to play the second singles against Alex De Minaur in Spain's tie against hosts Australia at the Rod Laver Arena but pulled out hours before his match.
"Hi all, we have decided with #TeamSpain and my team, to not play today the first match of the @ATPCup here in #Melbourne since I have a stiff low back," Nadal said on Twitter. "Hopefully I'll be better for Thursday."
Spain, who lost in the final of the inaugural ATP Cup last year, will play Greece on Thursday and Nadal would hope he would be fit to play the tie and get some match practice before the Feb. 8-21 Australian Open.
A spokesman for Nadal, who tied Roger Federer's 20 Grand Slam singles titles with his French Open victory last year, told Reuters that the 34-year-old preferred 'not to force too much'.
Nadal was replaced by Pablo Carreno Busta for Tuesday's singles match.
The Spaniard was one of the top players who quarantined in Adelaide for 14 days after their arrival Down Under.
At the end of his isolation, he defeated Dominic Thiem 7-5, 6-4 on Friday in a highly entertaining exhibition match between the men's world number two and three at Adelaide's Memorial Drive Tennis Club.