The 27-year-old Scotland captain joined the Reds from Hull in July 2017 for an initial fee of £8m and has made 177 appearances for the Anfield club.
Browsing: Andrew Robertson
With the game at 1-0 heading into stoppage time, Andrew Robertson was adjudged to have kicked the foot of Danny Welbeck in the box, and after going over to the pith side monitor, Stuart Attwell awarded the spot-kick, despatched down the middle by Gross.
The Gunners took the lead in controversial circumstances after 34 minutes played at the Emirates when the ball struck Sanchez on the hand on its way into the net