Toto Wolff says the Mercedes drivers may be unhappy with some calls . Lewis Hamilton and Nico Rosberg have fallen out after the Chinese GP . The German driver has been critical of his team mate in recent weeks, saying he is not happy at Mercedes' pace this season.
Toto Wolff says the Mercedes drivers may be unhappy with some calls . Lewis Hamilton and Nico Rosberg have fallen out after the Chinese GP . Ferrari are proving tough competition and Wolff says they must win .