Arsenal manager Mikel Arteta was spotted doing one thing immediately after Leandro Trossard put the Gunners ahead against Manchester United. Arsenal went to Old Trafford on Sunday afternoon knowing that only a win against Manchester United would keep them in with any kind of realistic chance of being crowned Premier League champions. Based on form alone, the Gunners will have been considered heavy favourites heading into this fixture. However, their poor record at Old Trafford, plus the scale of the potential prize at stake, will have added the weight of additional pressure on Mikel Arteta’s m…