Rafael Nadal's new high-tech tennis racket looks and feels like his old one. Except for the on-off switch.

Call it a "smart racket", the latest advance in tennis technology tells you where you hit the ball - with the help of an app. 

Sensors embedded in the handle of the racket, made by Babolat, record technical data on every ball struck. At the end of a match or training session the data can be downloaded to a smart phone or computer and used to help analyse a player's strengths and mistakes.

Sometimes it's not a good thing. Because you think you're hitting it in the middle of the racket, but really it shows you you're not.

Caroline Wozniacki, Former world number one

The International Tennis Federation had previously outlawed what it calls "player analysis technology'' during competition but adopted a new rule last January that allows players to wear or use "smart" equipment, like Nadal's new racket and devices like heart-rate monitors that record data about player performance in real time.

Babolat initially fitted the technology into its "Pure Drive'' rackets, which are used by Karolina Pliskova, Julia Goerges and Yanina Wickmayer and then incorporated the sensors into a newly released version of the "AeroPro Drive'' racket used by Nadal, Caroline Wozniacki and Jo-Wilfried Tsonga.

Don't expect to see players on their iPhones analysing their game mid-match. An ITF ban on coaching during matches prevents players from consulting the data on court.

Easy to use

The way it works is simple, says company spokesman Thomas Otton. There are two buttons on the bottom of the racket's handle.

"You press the `on' button. A blue LED light appears. And, you play,'' Otton said. When finished, a second button is pressed, activating Bluetooth which synchs the information with a smart phone or other device.

Otton called up Nadal's data from his practice session on Friday that lasted one hour, 31 minutes. In that time, he hit 572 shots, or 22 per minute, which broke down to 156 backhands, 222 forehands, 118 serves and 76 smashes.

The data also gets more detailed and analyses, for example, how Nadal hit his forehands - 133 had topspin, 49 had slice and 40 were flat.

Swipe to the next screen and an image of a tennis racket appears that shows where the ball is making impact. For Nadal's practice, he hit 42% of shots in the centre and 20% on top of the racket - the rest on the bottom and sides.

At a demonstration of the racket before the tournament started, Wozniacki and Nadal joked about the pros and cons of knowing too much.

"Sometimes it's not a good thing,'' said Wozniacki. "Because you think you're hitting it in the middle of the racket, but really it shows you you're not. And there's no going around that.''

Source: AP