Serbia's Novak Djokovic hits a backhand against Austria's Dennis Novak during a Davis Cup group F match between Serbia and Austria in Innsbruck, Austria, Nov 26, 2021. (MICHAEL PROBST / AP)

World number one Novak Djokovic overpowered Dennis Novak after Dusan Lajovic battled past Gerald Melzer and Serbia went on to a 3-0 win in their opener against Group F hosts Austria in the Davis Cup Finals in Innsbruck on Friday.

Djokovic, aiming to guide Serbia to their first title since 2010 and second overall, made light work of his opponent as he dropped just six points on serve and did not face a breakpoint while claiming a 6-3 6-2 victory in under an hour.

I felt very good. I was locked in from the first point, determined to execute the game plan.

 Novak Djokovic, world No1 tennis player

"I felt very good. I was locked in from the first point, determined to execute the game plan," Djokovic told reporters.

"The crucial game was the eighth game of the first set, 4-3, new balls. I managed to put in a couple of extra returns, make him play, mix up the pace. After that, there was really no looking back. I just served well, moved great."

Lajovic had a much tougher time against Melzer, the younger brother of fellow professional Juergen, as he was forced to toil for a 7-6(5) 3-6 7-5 win.

The 31-year-old squandered a break advantage in the third set but recovered to convert his fourth match point and seal victory.

"It is the Davis Cup. It is the emotions, the stress, the pressure. It is the tight moments all the time," said Lajovic. "He played some good tennis in the past couple of months, and had confidence and showed it today, playing great tennis.

Nikola Cacic and Filip Krajinovic made it a clean sweep for Serbia with a 7-6(4) 4-6 6-3 win over Oliver Marach and Philipp Oswald.

ALSO READ: Ruud beats Sultanov as Norway take lead in Davis Cup

Elsewhere, Lorenzo Sonego and Jannik Sinner secured emphatic wins in their singles rubbers to give Group E hosts Italy a 2-0 lead against the United States in Turin before losing the doubles dead rubber in straight sets.

Italy's Lorenzo Sonego returns the ball to United States' Reilly Opelka during their Davis Cup men's single finals tennis match at the Pala Alpitour in Turin, Italy, Nov 26, 2021. (ANTONIO CALANNI / AP)

Debutant Sonego got the Italians off to the perfect start with a 6-3 7-6(4) victory over big-serving Reilly Opelka with a disciplined display that included only one unforced error.

"It was not easy to play here, but this crowd... It's the first time in Davis Cup and I was so looking forward to this match -- thank you everyone," said the 26-year-old.

World number 10 Sinner, who made his debut at the season-ending ATP Finals this month, put the tie beyond doubt as he smashed 17 winners in a 6-2 6-0 thrashing of John Isner.

"Playing here was very special," Sinner said. "Today we have won already, which is great. We have a great team and everyone is a great guy as well, so we are just trying to stay together. I am very honored to be a part of this."

In Madrid, Feliciano Lopez and Pablo Carreno Busta helped holders Spain to an insurmountable 2-0 lead over debutants Ecuador.

Veteran Lopez breezed past Roberto Quiroz 6-3 6-3 before Carreno Busta fought back from a set down to beat Emilio Gomez 5-7 6-3 7-6(5) and secure victory for Spain.

Carreno Busta then returned for doubles action with Marcel Granollers and the Spanish duo earned a 6-4 6-7(5) 7-6(2) win over Gonzalo Escobar and Diego Hidalgo.