Jan Vertonghen injury: Tottenham defender barely able to stand as he is carried from the pitch in Champions League semi-final against Ajax

Kieran Trippier swung the ball into the box, only for Vertonghen and Alderweireld to clash heads while challenging Ajax goalkeeper Andre Onana for the ball

Tottenham Hotspur’s medical staff were left facing questions on Tuesday night after Jan Vertonghen was allowed to continue playing against Ajax after receiving a head injury, only for the defender to almost collapse just moments later.

The incident, which occurred in the first half of Tottenham’s Champions League semi-final, raises further questions about the treatment of head injuries in football, and whether players should be allowed to continue playing despite the risk of concussion.

Spurs were pinned back for large exchanges of the first half against Ajax, and conceded early on to the impressive Donny van de Beek, but enjoyed a rare attack when Christian Eriksen was fouled by Nicolas Tagliafico.

Kieran Trippier swung the ball into the box, only for Vertonghen and Alderweireld to clash heads while challenging Ajax goalkeeper Andre Onana for the ball. Both of the Belgian defenders collapsed to the turf, although Alderweireld was quickly back on his feet.

However Vertonghen appeared to suffer a far more serious injury, with both his shirt and shorts covered in blood.

After a lengthy delay, and a rousing reception from both sets of supporters, the former Ajax player changed his strip and attempted to carry on after a consultation between Belgian referee Antonio Mateu Lahoz and Tottenham’s medical team.

Tottenham’s medical team appeared to instruct the referee that Vertonghen was fit to continue, with the Belgian returning to the pitch. However he looked groggy and unsteady on his feet, before walking back over to the touchline.

Upon being replaced by Moussa Sissoko, Vertonghen then appeared to retch violently and had to be supported down the tunnel by both his manager, Mauricio Pochettino, and Tottenham’s team of physios. It is understood his condition improved once he returned to the dressing room.

Tottenham’s current injury crisis is already reaching breaking point. Spurs play Bournemouth away from home this weekend, before travelling to Amsterdam for the second leg of their first ever Champions League semi-final.