He simply had a bad game. Mendy was hardly shackled by the burden of defending yesterday, and Sané wasn't when he played wingback brilliantly last season.
For some reason people on here have to extrapolate 1 game into a permanent opinion and I just don't get it.
That wide role, call it wingback if you have to, saw Sané put in some amazing performances last season, and with only 1 LB, plus Aguero, Jesus and Sterling ahead of him in the running for the 2 striker roles in the 352, playing that position is something we might need him to do (just as well he did it brilliantly last season)