In a city with an operatic past, tennis is testing its future voice. In Milan, there are no linesmen on court and instead a computer is shouting "fault". Only John McEnroe would know how to argue with it.

Tennis was once played on an hourglass-shaped court and this week at the ATP Next Gen Finals - where new rules are being tried - they are using a court which looks slimmer because it has no doubles lines. No sport ever stays static because human taste never is. These days there is even salt in chocolate.

My father, who had to keep one leg on the ground when he served, is not sure why tennis must fiddle, but then change is always unsettling. It is life as you don't know it. Which is why hockey in four quarters still feels foreign and disqualifying a sprinter for just one false start is plain weird.

And yet change has strengthened sport. Without the three-point line in basketball we would not have had great Curry and even golf, starchy and dowdy, has had its moments. In the 1930s, golfers sometimes used 30 specialised clubs in a round till officials - and possibly exhausted caddies - limited it to 14.

Now in Milan we are a getting a glimpse of tennis' tomorrow. There are no lets and if a ball hits the net cord and dribbles over it could be an ace. There are no Hawk-Eye challenges to wait for on the giant screens - and thus no lurching of the heart - because now it's an all-electronic, line-calling world.

Even the warm-up before a match has been abbreviated to five minutes, though in truth it should be abandoned completely. Boxers don't get to throw practice punches because it's not their job to ready a rival. In the blue corner, Rafa, in the red corner, Roger: Let's go.

Change is amusing because often it reveals age or ideology. If you're raining down plagues on tennis officials this week then it's possibly because you're a traditionalist who can't quite believe spectators in Milan are allowed to move during play (except behind the baseline). No tense stillness, no respect to the performer, no hush?

No, that's so last century. And this is the truth of change, it's not aimed at us, but them, the kids who were beseeching players for autographs and the newer fans who might love the fact that there are no officious stewards telling them to wait for changeovers before wandering in.

They are the would-be recruits, we are the already recruited. We're so indoctrinated that we might watch 10 minutes of court No. 3 at a Bratislava Challenger at 2am. But tennis needs to seduce younger fans, appeal to their changing tastes, find a way to lure them away from F1, basketball, Netflix, Nintendo Switch, YouTube and whatever celebrity divorce is trending.

Change is both acceptance of and concession to the altering rhythms of life. Once the world took its time, now fast seems the only permissible speed. Even golf will try out a 40-second shot clock at next year's Austrian Open.

Broadcasters, alert to attention spans, love football's rigid 90 minutes and go pale when tennis stars wander into five-hour marathons. It is why if you look at the Next Gen Finals and its first-to-four-games sets (tie-breaker at 3-3), the 25-second shot clock and a sudden-death point at 40-40, it has one message: Don't dawdle, dudes.

Some of it is meaningful, especially the shot clock, because towelling off has become a painful, delaying nervous tic, to the point where a player asked for one the other day after being aced. Either way the changes are already working, in a sense, for they have started conversations and kindled debate. We're talking tennis, aren't we?

You say shorter sets heighten the tension, I say it is tennis which looks like a short story not a novel. You say there are more big points, I say points are big only when they are rare. You say electronic line-calling is futuristic and ends arguments, I say head-shaking, unconvinced players walking up to inspect ball marks like sneakered detectives is part of the little scenes that comprise the drama of tennis.

You say first-to-four-games sets is terrific, high-stress tennis, I say it discards the idea of comebacks, like the one Jack Sock made in Paris from 1-5 down in the third set of his opening round. He won the match, the tournament and qualified to play Roger Federer in the big-boys ATP Tour Finals tomorrow.

Bob Brett, former coach of Boris Becker, believes the changes can work in some events, but clarifies "this is like Twenty20 cricket but the Grand Slams are Test cricket". Yet tennis will keep experimenting for it is searching for an elusive harmony: to be glamorous but retain its soul; to be fan-friendly but not gimmicky; to speed up a game but also enhance it. It takes a little magic to make an almost 150-year-old sport look younger.

But it has to change because the Roger-Rafa show is running out of encores and younger fans are going to ask tennis: So what you got now? A hip game? Cool rules? Some old-timers might moan at all this and say "whatever happened to our world", but it's not theirs any more. The game respects the past but it always belongs to the future.