Roger Federer ended his remarkable career with an agonising doubles defeat alongside long-time rival Rafael Nadal at the Laver Cup in the early hours of Saturday.
The 20-time Grand Slam champion, dogged by a knee injury, has not played since the 2021 Wimbledon quarter-finals and last week announced his retirement at the age of 41.
But he rolled back the years in London, scene of many of his most famous triumphs at Wimbledon, to the delight of a feverish, partisan crowd.
Federer and Nadal – the pairing that tennis fans across the world were desperate to see – went down to Team World's Frances Tiafoe and Jack Sock 4-6, 7-6 (7/2), 11-9 at the O2 arena.
The result meant Team Europe were locked at 2-2 with Team World at the end of the opening day of the Ryder Cup-style event after Andy Murray slipped to defeat against Australia's Alex de Minaur.
"We'll get through this somehow," said a tearful Federer. "It's been a wonderful day. I told the guys I'm happy, not sad.
"It feels great to be here. I enjoyed tying my shoelaces once more, every thing was the last time.
"I didn't feel the stress so much even though I thought maybe something was going to go, like a calf, but the match was great.
"Playing with Rafa and having all the greats here, all the legends, thank you."
Federer has enjoyed a storied rivalry with Spain's Nadal over nearly two decades – together they have won 42 Grand Slam singles titles in a golden era for the men's game.
The pair, who first met in 2004, played 40 times, including in nine Grand Slam finals, with Nadal holding a 24-16 winning record.
But on Friday they were on the same side of the net in a fitting farewell for Federer, who turned professional nearly a quarter of a century ago.
There was a huge roar and standing ovation as the Swiss great and Nadal came onto the black court, dressed in blue shirts and white shorts, both wearing white headbands.
Both teams held serve fairly comfortably at the start of the match, with cries of "Let's Go Roger, Let's Go" breaking out at 3-3.
But Federer and Nadal seized on their first break point in the 10th game, winning the first set when Sock netted with a backhand to huge cheers.
The two superstars were rocked in the third game of the second set when Nadal was broken but they levelled at 3-3.
The second set went to a tie-break, which Team World won comfortably to force a match tie-break.
In a nerve-shredding shootout, Federer produced a vintage cross-court winner to level at 7-7 but he was struck on the arm by a Tiafoe shot on the next point.
Federer and Nadal were unable to capitalise on their single match point at 9-8, with their opponents winning the next three points to take the match.
The six-strong Team Europe also includes Novak Djokovic and Murray – the other two members of the so-called "Big Four", who dominated the men's game for so many years.
Italy's Matteo Berrettini will take Federer's place over the weekend as an alternate, with the Swiss great opting out of singles matches.
Europe have won all four previous editions of the Laver Cup and took a 2-0 lead after the opening session in London, courtesy of wins for Norway's Casper Ruud and Greece's Stefanos Tsitsipas.
Tsitsipas shrugged off a dramatic on-court protest by a demonstrator who set his arm ablaze to beat Argentina's Diego Schwartzman 6-2, 6-1.
The protestor, wearing a T-shirt that read "End UK Private Jets", was quickly dragged off court after water had been poured on his burning arm.
In the evening session Murray lost a gruelling encounter to De Minaur 5-7, 6-3, 10-7 before all eyes turned to Federer.
The Swiss is leaving the stage 19 years after winning his first Grand Slam title at Wimbledon in 2003.
He retires with a men's record of eight Wimbledon crowns, 103 titles overall and more than US$130 million in prize money alone, won with a game defined by a rare elegance and precision.
Nadal (22) and Djokovic (21) have both surpassed Federer's tally of Grand Slam titles but Team World captain John McEnroe said Federer's retirement would leave "a void that will never be filled". (AFP)