Dele Alli was hit on the head by a plastic bottle thrown from the crowd during Tottenham Hotspur's 2-0 defeat of Arsenal in the Carabao Cup quarter-final.
The incident took place 15 minutes after Alli had doubled Spurs’ advantage with a flicked chip off the outside of his boot during in the second-half at the Emirates.
Alli reacted by raising his two fingers to the crowd in reference to his team's lead.
Arsenal have said they have begun to examine CCTV in an attempt to identify the culprit.
Asked about the incident after the game, Alli told Sky Sports: "It is what it is. It made the goal a bit sweeter and the win."
Earlier this week, a Tottenham supporter who threw a banana skin at Pierre-Emerick Aubameyang in the Premier League fixture here just over a fortnight ago was banned from football for four years.
Tottenham will now face Chelsea in the semi-finals at Wembley, after the draw which took place immediately after the match. Manchester City will face League One Burton in the other semi-final
