Mercedes boss Norbert Haug has admitted that his team is unlikely to use its Coanda exhaust this weekend as it struggles to fully understand its affect, particularly on tyres.

As his team struggles to get the best out of the system, which it ran back-to-back with its old system in Austin, the Brackley outfit would rather focus on the 2013 tyres which will be made available for tomorrow's two practice sessions.

"We definitely start without," he told reporters at Interlagos, when asked if Mercedes would be using Coanda. "We want to do the tyre test without any influence. We have proper data with which we can compare what we had at the start of the year and then we'll probably leave it like that, we will see but no Coanda tomorrow.

"Why?" he continued. "Because we think that they still have an influence on heating the tyres, and both the combinations lack aerodynamic downforce which we could not approve compared to the others. So we think that we have a more realistic base to what we have had at the beginning of the season, and we work from there. But it's very clear that you have to have Coanda next year because it gives you a benefit."

Coming off the back of five races in which the team failed to score a single point, Haug was asked if there were plans for the Coanda system to make an appearance later in the weekend. "Not currently, no," was the response.