Geneva - Roger Federer edged out Nick Kyrgios in a super tie-break to give Europe a 5-3 lead after the opening session of the second day of the Laver Cup in Geneva on Saturday.
The 20-time Grand Slam champion, who won his first match alongside Alexander Zverev in Friday's doubles tie, beat Australian Kyrgios 6-7 (5/7), 7-5, 10-7 to the delight of his home crowd.
Bjorn Borg's holders had seen Team World draw level earlier with John Isner's victory over Zverev.
The 38-year-old Federer had won his last two matches against Kyrgios in straight sets, but dropped the opener in a tie-break.
But he hit back to level the match with a break in game 11 of the second set, before holding off a late Kyrgios rally in the super tie-break to take it on his third match point.
Later, Rafael Nadal will play his first matches of the weekend when he takes on Milos Raonic in the singles, before teaming up with Stefanos Tsitsipas to face Kyrgios and Jack Sock in doubles.
Earlier on Saturday, Isner fought back from a set down to beat Zverev 6-7 (2/7), 6-4, 10-1 and haul Team World level at 3-3 after Europe led by two points after the opening day.
The big-serving American lost a first-set tie-break, but hit back before racing through the super breaker in style.
"Maybe we're turning the tables just a little bit," said world number 20 Isner, the highest-ranked player in the visitors' team. "Team World is in this and we're here to win, so let's get it going."
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.
This year is the first time the tournament has been played since being added to the ATP Tour.
Europe won the 2018 edition 13-8 in Chicago.
Results from the third Laver Cup in Geneva on Saturday:
John Isner (World) bt Alexander Zverev (Europe) 6-7 (2/7), 6-4, 10-1
Roger Federer (Europe) bt Nick Kyrgios (World) 6-7 (5/7), 7-5, 10-7
Rafael Nadal (Europe) v Milos Raonic (Europe)
Rafael Nadal and Stefanos Tsitsipas (Europe) v Nick Kyrgios and Jack Sock (World)
Overall score: Europe 5 World 3
Note: On opening day, each win secures one point, on second day, two points, on third and final day, three points.