Watch: Bizarre scenes at Next Gen ATP Finals as Arthur Fils and Luca Nardi are forced to switch ends during a game after chair umpire's blunder

Arthur Fils and Luca Nardi were made to change ends in the middle of a game in a bizarre moment during their Next Gen ATP Finals match.

Fils and Nardi have been drawn in the Green Group alongside Dominic Stricker and Flavio Cobolli. They had a chaotic start to their campaign in Jeddah, Saudi Arabia on Tuesday, November 28, thanks to the tournament’s unique set of rules.

Several new rules and innovations are introduced at the Next Gen ATP Finals each year with the aim of enhancing the sport. ‘One sit-down per set’ is one such rule being implemented at the event.

According to the rule, there will be no changeover after the first game of the set and the players are required to change ends and sit down after the first three games are played. Unlike the usual ATP rules, they will then change ends after the conclusion of each set, regardless of the number of games played in the set.

However, after Luca Nardi clinched the first set 4-2, he and Arthur Fils forgot to change ends. The chair umpire, Mohamed Layhani, realized the blunder as Fils served to clinch the opening game of the second set at 40-0.

Without sparing a moment, Layhani corrected the mistake by asking the Frenchman and the Italian to switch ends immediately despite the opening game being underway. The chair umpire also apologized for his error.

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"Things can change very quickly" – Arthur Fils after defeating Luca Nardi in the Next Gen ATP Finals clash

Arthur Fils defeated Luca Nardi in their opening match at the Next Gen ATP Finals

The Next Gen ATP Finals showcases the eight best players of the season, aged 21 and under. World No. 2 Carlos Alcaraz, No. 8 Holger Rune, No. 17 Ben Shelton and No. 27 Lorenzo Musetti were among the qualified players this season, but they opted out of the event.

Arthur Fils, Luca Van Assche, Dominic Stricker, Alex Michelsen, Flavio Cobolli, Hamad Medjedovic, Luca Nardi and Abdullah Shelbayh (wildcard), who were next in line, thus made the cut.

Top-seeded Fils kicked off his run with a 2-4, 4-3 (6), 4-2, 1-4, 4-2 victory over seventh seed Nardi in the uniquely structured best-of-five sets, and a first-to-four-games scoring format.

“It was a tough match. The first time in my life I’m playing first to four games," the 19-year-old said in his on-court interview.

"Things can change very quickly. I was leading two sets to one, had break points, and I was feeling very good. Then I lost a deuce point and everything changed, but I’m really happy to win today,” he added.

In the match that followed, Green Group's Flavio Cobolli outclassed Dominic Stricker 4-2, 3-4 (7), 4-1, 4-2.