United’s goalkeeping coach, Emilio Alvarez, was deep in discussion with De Gea (Picture: MUTV)

David de Gea was hastily given some last-minute instructions by Manchester United’s goalkeeping coach in the tunnel after Arsenal surprisingly picked Alexandre Lacazette to start.

The Frenchman had been ruled out of Saturday’s match at the Emirates by Arsene Wenger, with United preparing to face either Olivier Giroud or Danny Welbeck in the days leading up to the match.

But Lacazette’s inclusion took United by surprise – and Mourinho admitted as much beforehand – and De Gea appeared to still be given some tweaked advice just minutes before kick-off.

De Gea and Alavrez spoke for several minutes as the rest of the players lined up (Picture: MUTV)

Emilio Alvarez, the goalkeeper coach who was brought in last summer specifically on De Gea’s request, made a rare appearance in the Emirates tunnel complete with a clipboard.

He and De Gea were deep in conversation while the rest of the squad lined up, and it is entirely possible they were going through tactics for stopping Lacazette.

Alvarez and De Gea studied a clipboard while the rest of the squad got in the zone (Picture: MUTV)

The £50m summer signing from Lyon is now Arsenal’s designated penalty taker, and goalkeepers spend hours studying penalty techniques, run-ups and shot locations to try and second guess where they will put their spot-kicks and shots.

With Lacazette out, De Gea would have memorised and practiced for facing Alexis Sanchez – the club’s deputy penalty taker – but seemingly needed a crash course in what to expect from Lacazette.