The challenge drew a mixture of disbelief and hilarity when it happened, such was the unconventional nature of it.
While on the half-way line, Tottenham forward Lucas Moura knocked the ball past Ralls.
With the Cardiff midfielder being outdone for pace, he slid across to blatantly block the player, with the ball nowhere near his feet as he slid in, and was given an imediate dismissal.
Now, the Wesh club have decided to appeal the decision to try and get it over-tunred, but if not successful Ralls will have to sit out at the next three games.