Mercedes is talking to potential candidates to become the team's test and reserve driver in 2011.

Before returning to the grid last year with Sauber, Nick Heidfeld started 2010 in the third role at Mercedes.

But the marque's head of marketing Joachim Schmidt suggested that a non-German will be appointed for this season.

"We already have two German drivers," he told the Bietigheimer Zeitung newspaper, referring to the unchanged race line-up including Nico Rosberg.

"At the moment we are in conversation with potential candidates," added Schmidt.

Mercedes had a difficult first year away from long-time partner McLaren, finishing the constructors' championship just fourth despite having Michael Schumacher on board.

But Schmidt insisted: "The financial burden, compared to when we were partnered with McLaren, is clearly lower.

"For us, because of the advertising revenue and the money from FOM, it is economically more attractive than before.

"For this reason, we have the backing of our workforce for our Formula One engagement."