If his deadly backhand is working , he can heap misery on anyone on a given day .
Federer holds a 3 - 1 edge this year but Wawrinka won a very important clash at the French Open .
If Wawrinka 's deadly backhand is working , Wawrinka can heap misery on anyone on a given day .
Federer holds a 3 - 1 edge this year but Wawrinka won a very important clash at the French Open .