Mercedes F1 boss Niki Lauda launched a verbal grenade at Nico Rosberg . The three - time heavyweight champion urged Rosberg to step up his belt . Lauda has called for Rosberg to challenge Lewis ##da all the way . Austrian champion Rosberg is extremely professional but lacks patience .
Mercedes F1 boss Niki Lauda launched a verbal grenade at Nico Rosberg . The three-time world champion wants Rosberg to step up his game . Lauda has called for Rosberg to challenge Lewis Hamilton all the way . Austrian believes Rosberg is extremely professional but lacks confidence .