Casemiro was sent off for Manchester United after goalkeeper Andre Onana made another glaring error for the Red Devils against Galatasaray on Tuesday night.
Onana has struggled to make his mark in his first few games at Old Trafford, with the 27-year-old having already been responsible for several high-profile mistakes.
Another high-profile mistake came against Galatasaray on Tuesday when Onana needlessly gave the ball away to Dries Mertens, who was fouled by Casemiro as he raced into the box.
The Brazilian midfielder was then shown a second yellow card by the referee and given his marching orders, although Mauro Icardi went on to put his spot-kick well wide of the post.