Manchester United defender Matthijs de Ligt suffered an injury in the build-up to his side conceding a goal against Brentford.
Despite De Ligt clearly being in pain after colliding with Bryan Mbeumo, play was allowed to continue, with Kevin Schade proceeding to put Brentford in front in the 33rd minute.
Shortly afterwards De Ligt had to be substituted, with Harry Maguire replacing him.
It is the second time that such an incident has occurred involving de Ligt against Brentford this season.
In October the Dutchman was left with a bloodied head following a clash with Schade at Old Trafford.