MONTREAL, Canada - Amid the most successful period in his Formula 1 career to date, the frustration has often shown on Nico Rosberg's face.As journalists dutifully asked a few sporting-related questions in Canada, SID news agency revealed that Rosberg "rolled his eyes" and put on a "tortured smile" as he asked the press: "Can we come to the tyre issue now, please?"DARK DAYS He was sarcastically referring to the Pirelli-Mercedes test row, a scandal of typical F1 proportions that is questioning Mercedes' fairness and integrity just as Rosberg delivered a hat-trick of poles and a lights-to-flag Monaco victory.Team director Toto Wolff, however, insists Rosberg is "not frustrated because he's too professional" and it is, after all, "a management issue".Rosberg said: "How important is it, what others say or write?"Wolff insisted Rosberg is telling the truth on that score: "He is a disciplined thinker, blessed with great talent. He can always extract his very best performance, because he can put aside everything else and focus only on the sporting side."Wolff, meanwhile, is more open about his own frustration.Wolff said: "Of course, for whatever reason, people are always looking for the controversy."Maybe that's even more unpleasant for us because we are now more competitive - that the controversy is coming across in the media as more important than the drivers' performance." Stay with Wheels24 for the 2013 F1 season – fresh reports every day.