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 here on Saturday.
The 20-time Grand Slam champion, who won his first match alongside Alexander Zverev in Friday's doubles, beat Australian Kyrgios 6-7(5), 7-5, 10-7 to the delight of his home crowd.
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 win on his third match-point.
Earlier, Isner fought back from a set down to beat Zverev 6-7(2), 6-4, 10-1 and haul World level at 3-3 after Europe led by two points at the end of the opening day.
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.
On Friday, Federer and Zverev claimed a hard-fought 6-3, 7-5 victory over Jack Sock and Denis Shapovalov.
Europe won the 2018 edition 13-8 in Chicago.
The results:
Europe leads World 5-3 [Alexander Zverev lost to John Isner 6-7(2), 6-4, 10-1; Roger Federer bt Nick Kyrgios 6-7(5), 7-5, 10-7; Federer & Zverev bt Jack Sock & Denis Shapovalov 6-3, 7-5; Stefanos Tsitsipas bt Taylor Fritz 6-2, 1-6, 10-7].
