Roger Federer and Alexander Zverev claimed a hard-fought doubles victory over Jack Sock and Denis Shapovalov to give Europe a 3-1 lead over Team World after the opening day of the third Laver Cup in Geneva on Friday.

The 38-year-old Swiss delighted his home fans alongside Zverev, as the European pair saw off Shapovalov and Sock 6-3, 7-5 after a dramatic second set.

"All of us tennis players travel around the world for 10, 11 months of the year," Federer told a capacity 18,400-crowd at the Palexpo arena.

"There's no place like playing at home, so this is a very special night for me."

American Sock had earlier defeated Fabio Fognini 6-1, 7-6 (7/3) in the singles to draw John McEnroe's visitors level after Dominic Thiem's win against Shapovalov.

But Greek star Stefanos Tsitsipas restored Europe's advantage by downing Taylor Fritz in a super tie-break to win 6-2, 1-6, 10-7, and Federer and Zverev combined to put Europe in control.

The home duo served out a tight opening set after a single break of serve on their fifth set point, but the match came to life in the second.

Shapovalov and Sock broke Federer in the eighth game to level the set at 4-4, before seeing six set points come and go when Zverev was serving at 4-5.

The rest of Bjorn Borg's Europe, including an animated Rafael Nadal, ran to Federer and Zverev's bench to congratulate their teammates on then breaking in the 11th game, and the 20-time Grand Slam champion confidently served out the match to prevent a super tie-break.

Earlier on Friday, Thiem staved off three match points to beat Shapovalov in the opening tie.

The two-time French Open runner-up recovered from 9-7 down in a super tie-break to win 6-4, 5-7, 13-11 against Canadian youngster Shapovalov.

"It's a really special thing with the tie-break in the third, it creates lots of close moments and match points on either side," Thiem said. "It's also a little bit of luck at the end."

Sock's victory over Fognini was his first in singles on the ATP Tour this year.

The world number 210 held his nerve in a second-set tie-break to become the first World player to ever win an opening-day singles match, as Fognini was left stunned despite receiving a pep talk mid-match from Federer.

Holders Europe are red-hot favorites to retain the trophy, with Borg's side facing a visiting team whose highest-ranked player is world number 20 John Isner.

The scoring system sees one point awarded for each win on the first day, two points given for each victory on the second day, and three points on offer in each match on Sunday's final day.

Europe won the 2018 edition 13-8 in Chicago.