Definition of Cup Tied

What is the meaning of Cup Tied in the game of football?

A football player is said to be cup-tied if he is not able to play in a cup competition (UEFA Champions League for example) due to the fact that he already played in the same competition for a different team during the same season.

This usually occurs when a player changes teams during the winter transfer window.

A good example is Juan Mata, who transferred from Chelsea to Manchester United during the 2013/14 season winter break. Juan Mata played for Chelsea in the UEFA Champions League and because of that he is not able to play for Man Utd in the same tournament for the rest of the season.

This rule exist to prevent wealthy teams from buying players from smaller teams that they are up against in the cup.