Barcelona, Borussia Dortmund, Inter Milan and Slavia Prague are in the same group of the Champions League.
The Borussia Dortmund Twitter account could not resist the opportunity to take a cheeky dig at Barcelona.
Last Season Barcelona were defeated 4-3 on aggregate by Liverpool in the semi-final.
The winning goal was scored thanks to fast thinking by Trent Alexander-Arnold, who took a quick corner while Barcelona appeared to be switched off to set up Divock Origi for the decisive strike.
The Dortmund account reminded them of this incident with a simple post which read: "Time to practice our corners."