Mercedes remains confident ahead of Thursday's FIA tribunal hearing into the alleged illegal test that team completed with Pirelli in Barcelona last month.

Team principal Ross Brawn has always maintained that the Brackley-based squad had done nothing wrong, claiming that FIA sanctioned the outing and the use of the 2013 Mercedes car, but the Silver Arrows still find themselves in the dock, with the threat of potential sanctions hanging overhead.

Director Toto Wolff has now added his voice to the fray, echoing Brawn's claims and insisting that Mercedes done all it can to be prepared to defend its case.

"We have prepared our documents, we can do no more," Wolff, who won't be present at the Paris hearing, told German newspaper Welt am Sonntag, "On Thursday, the judgement comes and we will see whether we can live with it. We have no feelings, neither a positive nor a negative, [but] our belief is we have done nothing wrong."

Mercedes' defence is expected to focus on an email it claims to have received from FIA safety delegate and race director Charlie Whiting, sanctioning the use of its current car in a bid to help Pirelli address safety concerns with its 2013 tyres, which had suffered delaminations at successive races in Bahrain and Barcelona. Mercedes' involvement was as a direct result of being on the receiving end of one of those failures - and a previous willingness to aid Pirelli - but has alarmed rivals, who feel that it gained vital development miles for its W04.

"Mercedes are ready to play their trump card, in the form of an FIA email - allegedly from their race director and safety delegate, Charlie Whiting - granting them permission to test," Britain's Guardian newspaper confirmed, backing up Brawn's claim that there were still details set to emerge at the tribunal.

The Briton has remained calm throughout the accusation process, and appeared confident of success when facing a barrage of questions during the Friday press conference in Montreal recently, in contrast to those who have railed against the test.

Plans to introduce a revised version of Pirelli's medium tyre - one of those allegedly tested by Mercedes in Spain - have been abandoned, at least for the time being, after the Italian supplier failed to convince all eleven teams of the merits of change.