Belgian defender Jan Vertonghen threw his support behind Anderlecht tonight.
Arsenal and Tottenham may have already played out a 1-1 draw at the Emirates Stadium earlier this season, but the rivalry between the clubs continues to generate interest.
After goals from Alexis Sanchez, Mikel Arteta and Alex Oxlade-Chamberlain, Arsenal were coasting to a 3-0 win over Belgian side Anderlecht.
Yet the Gunners fell apart in the second half, as former Portsmouth full back Anthony Vanden Borre grabbed two goals to set up a nervy finish at the Emirates Stadium.
And then, with the game set to end, Serbian youngster Aleksandar Mitrovic planted a diving header past Wojciech Szczesny into the corner of the net to hand Anderlecht a point.
It was a stunning collapse from Arsenal, and fans were clearly unhappy after the game - and one Tottenham player didn't help their cause.
Defender Jan Vertonghen is a Belgian international, so his allegiance was naturally not just against Arsenal, but also in support of the club from his country.
When Mitrovic's header hit the back of the net, Vertonghen took to Twitter to celebrate - shown below - much to the anger of Gunners fans, who fired insults at the centre back.