I got humbled by a £2,599 tennis robot

Half an hour into an intense training session on the courts of Coolhurst Tennis Club, I simply cannot get the ball past my practice partner. It's as if they're on wheels. Hang on, they are on wheels. 

Uncanny defence, infallible accuracy, a resolute indifference to sledging: these are among the virtues of the Acemate Tennis Robot S10 : an opponent that appears to have no weakness.

As the fuzzy yellow missiles fizz towards me, I find myself sympathising with the protagonist in HG Wells's The War Of The Worlds – a man whose unequal battles with Martian fighting machines left him contemplating "my own feebleness and anguish".

And yet, there is one chink in the Acemate's armour. Just as Wells's Martians were eventually brought low by humble bacteria, so this expensive device is best left inside when it's raining.

As it happens, the day we have chosen at Coolhurst is fine and dry – but happily not too hot. Because it is an exhausting business, playing tennis against a robot.

The machine accepts up to 40 balls in its giant metal "pocket". But if you are using it right, you shouldn't need more than a few of them.

The unique virtue of this nifty bit of kit is that it collects your shots as you hit them, using its two cameras to line up the ball and then whizzing sideways in a long, sweeping curve to intercept it.

The top of the unit is like a giant butterfly net, or perhaps a catcher's mitt, with extensible arms that pull out to a height of 5ft 7in. From its stature, this could be a mechanised Arthur Fery.

Even as one ball is disappearing down the Acemate's gullet, another pops out of its mouth, thus simulating the rhythm of a normal rally. And this is where it scores over other hi-tech practice partners, like the Pongbot Pace S Pro which I have also ferried to Coolhurst in tennis's answer to Robot Wars .

Any clubbie should be familiar with the claustrophobic feeling of hitting against a superior player. Duelling with the Acemate evokes a similar sense of being rushed all the time. And just to add to the challenge, the robot keeps catching your eye as it buzzes around the far end of the court, like a hyperactive hound that won't come to heel.

How then, do you exhaust the Acemate's theoretically endless supply of balls, and thus avoid an infinite rally? Well, if you wanted to cheat, you could simply miss the court entirely, or even shoulder arms like an England cricketer misreading the line. But that, clearly, would be a cop-out.

If by any chance you have a particularly whippy swing, with lashings of heavy top-spin, you might be able to make the ball leap up off the court and fly over the top of the catching net.

But your best options are either to hit with such pace that you beat the defensive-sweeper manoeuvre, or – assuming that the Acemate has not retreated behind the baseline – to fire the ball in deep and low, so that it effectively nutmegs the net and slams into the metal face of the robot itself, which resembles a rectangular roller-skate.

The Acemate's uncanny ability to scoot around in any direction employs the so-called "Swedish wheel" technology developed in the 1970s, which is now the norm for all sorts of autonomous robots, whether they dispose of bombs or collect packages from warehouses.

I looked this up on YouTube and found an enthusiastic science nerd comparing the Swedish wheel's mechanics to Michael Jackson's moonwalk. Which feels appropriate when you are up against the third cousin, once removed, of a lunar roving device.

The Acemate is controlled from your iPhone, which should in theory stop it from turning rogue and logging into Skynet. Initially, I set it up to play nice. But then my camera-wielding colleague Belinda grabbed the phone and increased the difficulty level.

At first, with the balls coming centrally, I managed to drive a few winners past (Ace) matey-boy. With luck, my page-building colleagues will select one of these occasional flashes of competence to illustrate this article – although experience suggests that they will opt for something more humiliating.

Then, as Belinda turned sadistic, I found myself shuttling left and right to the corners of the court until the sweat ran down my back and every one of my shots was either dying in the net or flying long.

I cast my mind back to Red Dwarf , the BBC spaceship sitcom, in search of the sort of verbals that were regularly aimed at Kryten the Series 4000 robot. "Demented Tonka toy", I essayed. "Bog-bot from Hell". No effect at all.

Meanwhile, the Acemate app was busy preparing its own withering, AI-enabled assessment of my game. "You can keep the ball in play and maintain safe height," it told me, in a gently condescending tone. "But consistency over longer rallies and directional control are still developing."

Still developing? I'm 52. At this rate, I'll be graduating from the "beginner" category at around the same age that I'm ready to retire.

Time to power down the Acemate and switch on the Pongbot Pace S Pro, a Chinese-made alternative that lacks its rival's wow-factor but comes in at around half the price. I found a Pongbot quoted at £880 on Amazon whereas the American Acemate goes for £2,599 on its official UK website, or £2,199 on a sale day.

The Pongbot also has wheels, but they are only used to push it, suitcase style, on to the court. Then it simply sits there and rotates on its base like a hi-tech cannon, following your instructions as to where you want the ball fired.

Because it has no cameras, it comes with three bluetooth-enabled clips, like fancy clothes pegs. You place two on the net, in line with the sidelines, and the third on your own collar, so that the machine can orient itself in space. It works out when you have recovered from your last shot, and only then does it feed you the next one.

How do the robots compare with human practice partners? Well, the Acemate's post-match chat isn't its strength. On the upside, though, these devices can be set to perform at a variety of levels, whereas I cannot just ask my mate Sascha to "play better" without him bopping me on the nose.

What's more, you can invite a robot to focus on the precise part of your game which needs attention, making it more akin to a coach than a rival. Take 20 lessons at your local club at £40 a pop and you're already moving into Pongbot pricing territory.

The only problem is the relentlessness of it all: a bonus for young whippersnappers but a stretch for old codgers like me. As the temperature climbed at Coolhurst TC in north London, I wheeled the Acemate to one side of the court, the Pongbot to the other, and left them to fight it out.

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