The Champions League has a certain resonance at Manchester United. Of course, the competition means a lot to every team that contests it, but for England's most successful team, there's an added romance. And in the last few months that romance has turned into crippling pressure. It could be David Moyes' only chance of making an impression this season.
However, as United resume their European campaign against Olympiacos on Tuesday night, one of their most important players will be sidelined. Juan Mata will not miss out through suspension or injury, but because he has already played for another team in the Champions League this season. He's "cup tied," as they put it.
And he's not the only one who will miss out as the second round of knockout games kick off this week. Nemanja Matic, who played in the group stages for Benfica, is also cup tied as Chelsea take on Galatasaray in the competition's last 16.
But what purpose does this rule serve? By forbidding players that have switched teams mid-season to play in the second half of the Champions League, what is UEFA achieving? And what are they trying to imply?
Introduced decades ago, the fundamental point of the rule is to prevent wealthy teams from gaining an advantage by signing players who have been knocked out in the earlier rounds of European competition.
European football's governing body is trying to stop skullduggery before it even becomes a possibility. The principle intent is laudable, but in practice it just doesn't work like that.
Supporters want to see the best players in the best games, something that they are being denied with the banishment of Mata and Matic from the rest of this season's Champions League.
Why is Mata allowed to play for United in the Premier League, having turned out for Chelsea earlier in the season, but not in the Champions League? Sure, the Spaniard will not face Chelsea as an opponent in the league this season, but there's no rule that says he couldn't have played against his former team.
If the mid-season exchange of players makes UEFA feel uneasy, how can they justify the permitted fielding of loan players? Thibaut Courtois has played six games for Atletico Madrid in the Champions League this season and he's not even their player!
Chelsea, a team Atletico could face in the latter stages of the tournament, own him. And seeing as it can't be stipulated in a loan deal between European clubs, Courtois could even play against his parent team!
It is an outdated rule, and its application is muddled. In England, it applies to the FA Cup but not the Capital One Cup. Why? Nobody seems to really know.
With the introduction of transfer windows and squad restrictions, clubs can no longer buy players for certain games or stockpile them throughout the season. The central purpose of the rule has been undermined by the progression of the sport. Its relevancy has long since worn out.
Furthermore, the rule actually causes more manipulation than it prevents. How can clubs put off potential suitors for their best players? By cup-tying them, of course.
It can even have the opposite effect, with clubs preserving the value of a certain player by holding them back from playing in Europe early in the season, therefore increasing his appeal to a potential buyer. For instance, Michael Owen was benched for Liverpool's 2004 Champions League qualifiers ahead of his move to Real Madrid (who were ironically knocked out in the first round).
There have been a number of high-profile cases when it comes to the cup-tying of players. Brazilian striker Ronaldo was refused the chance to play for AC Milan in the Champions League the year the Serie A club went on to win the competition, having played for Real Madrid earlier in the season.
Andrei Arshavin had to wait until the 2009/10 season to make his Champions League debut for Arsenal, despite joining the Gunners in January 2009. He'd played for Zenit St Petersburg in the group stages.
"If you ask me would I like Arshavin to be with us, then I would say yes," commented Arsene Wenger before a European game against Villarreal, as per Arsenal.com. "But when I bought him I knew he would not be available, so I cannot complain about that."
Mata will take his place in the stands, perhaps alongside the emperor himself—Sir Alex Ferguson—for Tuesday's game. He will likely be only a few seats from the attending UEFA delegate.
The Spanish midfielder should ask why he's not allowed to play for his new team. And then pass on the explanation to the rest of us.