Britain's Cameron Norrie lost on his Laver Cup debut as Taylor Fritz beat him to pull Team World level with Team Europe after day two's opening session.

Matteo Berrettini had put Europe into a 4-2 lead with a 7-6 (11-9) 4-6 10-7 win over Felix Auger-Aliassime.

Roger Federer, who finished the final match of his career in the early hours of Saturday, was on the bench to support Norrie and Berrettini.

Federer was also coaching the Italian world number 15 - which Berrettini described as surreal because the Swiss great had inspired him to become a professional tennis player.

"It's actually weird, because when you're on court you're not thinking, oh my God, Roger is coaching me," said Berrettini.

"But then when you finish the match, you're like, wait, what? Last night, for example, one of the reasons why I couldn't sleep is because Roger had been crying on my shoulder [during his farewell match]."

Federer, 41, played alongside Rafael Nadal in the doubles as he waved goodbye to his 25-year professional career on an emotional night.

Nadal, whose wife is expecting their first child, only went to London to play in Federer's farewell and has now returned to Spain.

Players from each side are usually required to play at least one singles match in the annual three-day event.

The teams were level at 2-2 at the end of the opening day, when one point was given to each victory, after Federer and Nadal lost to American pair Jack Sock and Frances Tiafoe.

Each match win is worth two points on Saturday and three points on Sunday, with the first team to earn 13 points declared the winners.

Federer's retirement has been quickened by a knee injury, which meant he was only fit enough to play doubles and was replaced by Berrettini for the singles.

British number one Norrie, 27, was the second alternate for Team Europe and played as a result of Nadal's departure.

Saturday's night session sees Europe's Novak Djokovic play World's Frances Tiafoe in the singles, with the 35-year-old Serb teaming up with Berrettini against Sock and Alex de Minaur in the doubles.

Djokovic has not played competitively since winning Wimbledon in July, having been prevented from playing in the United States because he is not vaccinated against Covid-19.