LONDON, ENGLAND - OCTOBER 4: Alexis Sanchez celebrates scoring the 3rd Arsenal goal during the Barclays Premier League match between Arsenal and Manchester United at Emirates Stadium on October 4, 2015 in London, England. (Photo by Stuart MacFarlane/Arsenal FC via Getty Images)

LONDON, ENGLAND - OCTOBER 4: Alexis Sanchez celebrates scoring the 3rd Arsenal goal during the Barclays Premier League match between Arsenal and Manchester United at Emirates Stadium on October 4, 2015 in London, England. (Photo by Stuart MacFarlane/Arsenal FC via Getty Images)