The tweaks to the nose were spotted during Thursday's preparation day, but it is unclear yet what the testing plan is and whether or not the concept will be fitted for the entire weekend.

It is possible also that the extra raised bit of bodywork is just a trial to evaluate the aerodynamic impact of the required higher nose section for the 2016 car.

Giorgio Piola's exclusive photograph of the nose shows the new section, with the raised part in the centre.

The S-duct helps channel air from underneath the car to the top of the nose section to improve the flow, in theory helping the air move faster and therefore increasing downforce.

The idea of the S-duct first came from Ferrari in 2008, before being resurrected by Sauber who saw the benefits of it with the new high-nose cars in 2012.

The idea has been copied by a number of teams , including Red Bull, Toro Rosso, Force India and McLaren.

Mercedes has kept tight-lipped about the new bodywork, and used silver tape to hide the exit vent on the car on Thursday.

Continued push

Mercedes' introduction of the S-duct, despite having sewn up both world championships, shows how hard it is still pushing with development.

It comes amid a feeling that rivals Ferrari will be much tougher competitors next year, which means Mercedes needs to make good gains this winter.

Speaking earlier this week, Mercedes non-executive chairman Niki Lauda said: "The picture will change in 2016, because in F1 you can't sustain your technical superiority for a long time.

"We know the others can catch up. When you are at the limit of the performance of the regulations it's difficult to make big progress, which is easier for those behind us."