LONDON (Reuters) - Keith Glass took the balls to serve during the second set of his match against Anthony Fawcett in the 1975 Surrey grass court championships and served, and served and served... and served.
Eighty points, and 37 deuces, later, in which time an adjacent match started and finished, he finally won the game.
He lost the match, fatigue getting the better of him, but gained a place in the record books as having contested the longest single game ever recorded.
Such freakish passages of play are rare, but are what make the unique tennis scoring system, with origins in the 16th Century, a thing of wonder.
The principal of winning a game by two clear points, or a set by two clear games, is ingrained in the psyche of club hackers and elite pros alike -- so much so that the almost ubiquitous deciding set tiebreaks still rankle with many.
Wimbledon remains true to tradition, as demonstrated in bizarre circumstances in 2010 when American John Isner and Frenchman Nicolas Mahut contested the longest match of all time -- an 11 hour five minute monster spanning three days in which the 138-game fifth set alone lasted eight hours and 11 minutes.
Which is why the inaugural Next Gen ATP Finals, which concluded in Milan on Saturday, caused such a stir.
The event, showcasing the best players in the world aged 21 and under, ripped an ace through the rulebook with a raft of innovations the ATP claim can "re-invent" tennis.
Shot clocks enforced the 25-second between points rule, warm-ups were shortened, and sets were to four games not six, with tiebreaks at 3-3. Even service lets were scrapped.
The crowd could eavesdrop as players discussed tactics with their coaches via enormous headphones and line judges were replaced by live Hawkeye calling.
Even the court looked different, with doubles lines removed and a huge mock-up of Milan's La Scala at one end complete with a resident DJ pumping out tunes at changeovers.
It was tennis but not as we know it.
Gimmicky perhaps, but the good-sized crowds loved the rock and roll tennis served up by the exciting talents such as Denis Shapovalov, Andrey Rublev and Chung Hyeon -- three players tipped to fill the void when Roger Federer and co retire.
The players bought into the experiment, producing some eye-catching duels. However, while they were positive to some of the new rules, messing with the scoring system touched a nerve.
In Milan, the first deuce effectively became a 'sudden death' deciding point, meaning games could contain a maximum of seven points, 73 less than Glass's epic.
ATP chief executive Chris Kermode, trying to balance tradition with the task of future-proofing the sport, said the quickfire scoring reduced "dead periods" in matches.
The players, willing guinea pigs, were lukewarm about it.
Russian 20-year-old Rublev suggested it reduced a tight match to a 'lucky dip'.
"With these rules, everyone can beat everyone and I don't think that's very fair," he said. "The winner should be the guy who works harder for it."
While the best-of-five set format meant players still required to win 12 games for victory -- as they do on the regular ATP tour -- matches often resembled a series of short sprints.
Missing were the elongated games, the mini-battles that often decide who wins the war.
In this brave new world, the mesmerising 13-deuce game between Novak Djokovic and Stan Wawrinka in the 2013 U.S. Open semi-final or the 20-minute game won by Steffi Graf in the 1995 Wimbledon final against Arantxa Sanchez Vicario would not exist.
"I think tennis would lose something, it would become more clinical" Glass told Reuters. "But they said the same about tiebreaks and they are appreciated now. But I would be sad if they decided this was the way to go."
Kermode said no changes to the scoring would happen in the next five years but said in 10 years it was conceivable, saying there had already been interest from tournaments directors of the often struggling ATP 250 events.
It is unlikely to ever affect Federer, but the 19-times grand slam champion, while admitting to enjoying watching developments in Milan, has urged caution, saying it could rob the sport of its variety.
"Longer sets allow you to stretch a lead, try different things," he said. "You can work on stuff -- whereas, when every point counts so much, there's no room for anything any more."
The debate will rage on but in this time-hungry technological age, tennis cannot afford to stand still.
(Reporting by Martyn Herman, editing by Pritha Sarkar)