Claire Rafferty, the Chelsea and England left-back, thumps the ball goalward, prompting a cheer from a nearby iPad. Crouched over the screen a few seconds later she seems satisfied. "Did I get it over the wall? I'm gonna say yes. Happy with that."
Despite resembling an ordinary football, and having the dubious accolade of being Fifa-approved, the Adidas miCoach Smart Ball contains complex sensors embedded in a tiny "pit", like the stone in a cherry. The pit is suspended at the centre of the bladder by elasticated struts, allowing it to precisely gauge the spin, power and trajectory of the struck ball. Mechanics of this complexity, housed in a casing durable enough to repeatedly withstand the left boot of an international footballer, don't come cheap – the ball costs £250 – but Rafferty is impressed.
The Chelsea training ground in Surrey is a modern environment, with inflatable domes and big screens for reviewing match clips mid-practice. "They're working on underground heating on one of the pitches" says Rafferty, "you could probably live out here." An e-football, however, is unheard of thus far. "We used to have this wall you could kick a ball at which would tell you how fast you kicked it. This technology would be a first for us, it's innovative, and it could be very effective."
The ball doesn't only provide instant feedback on individual kicks, it also demonstrates the exact physics of the ball's flight through elegant graphics within an app, plots each kick on various graphs and provides extensive instructions for improvement. Rafferty scrutinises these after her second attempt – a Ronaldo-style spinless dipping kick. "I'm more of a whipper," she says, dissatisfied.
The Smart Ball is designed to help with all dead-ball situations – free kicks, corners, goal kicks, penalties. "Don't mention penalties!" pleads Rafferty, "I missed a penalty in the World Cup!" It is a pertinent memory. "At the top level, in a World Cup, that fine detail is win-or-lose. I could have done with one of these."
If Rafferty sees the Smart Ball as a professional tool, to be used in centres of excellence like the one at Millwall where she trained, is it also worthwhile for amateurs? "I would have begged for one of these from my mum when I was little. But obviously you'd have to take extra care not to kick it over a fence, and it's obviously more a Christmas present than an impulse buy."
This last concession is, perhaps, another kind of professional opinion: Rafferty also works three days a weekas a business analyst for Deutsche Bank. "My manager is very lenient," she explains, "I can leave early for away matches."
The Smart Ball may not be a panacea for all technique troubles, but Rafferty is smitten. "A lot of goals are scored from dead-ball situations, but of course there's more to winning games than free kicks. I mean, you have to be able to dive on the floor to get the free kick!" With this, she tees the ball up again and awaits the signal from the iPad. "This time, I'm going for an absolute spinner."