Former Arsenal full-back picked up an injury in an unusual manner during his side's 2-2 draw with Barcelona on Saturday.
The 33-year-old injured himself by celebrating his team's goal with teammate Mikel Oyarzabal, much to the amusement of former Manchester United player Adnan Januzaj.
Sociedad took the lead in the game, through a 12th minute penalty from Oyarzabal, before goals from Antoine Griezmann and Luiz Suarez turned the game on its head.
However, Alexander Isak struck in the 62nd minute to earn a hard fought point for Real Sociedad against the Spanish giants, much to the delight of Monreal.
In celebration, the defender ran over to Oyarzabal, but the teammates clashed in midair causing Monreal to need the physio in order to get treatment for a face injury.
The former Arsenal continued the game, and helped his side see out the draw.
Januzaj has since posted the clip of the celebration on social media, and has used the incident to joke with Monreal.
Posting on his Instagram story, the Belgian approaches the defender and asks "You feeling good bro? You feeling good?"
Monreal replies tongue in cheek with: "I don't understand."
Some fans also noticed the incident that led to the unusual injury.
The Spaniard played 251 games for Arsenal, scoring 10 goals and providing 20 assists. He left the club on deadline day.
