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Rui Vieira/Associated Press

One of the features of Jose Mourinho's first season in charge of Manchester United has been his use of a variety of formations. In general, he has alternated between contemporary football's most used systems, 4-2-3-1 and 4-3-3, but there have been cameos for a back-three formation and even an old-fashioned 4-4-2.

It is important to note that formations may look rigid on paper but are anything but in practice. United are particularly fluid in this sense because their systems are generally formed from flexible attacking players. Not one of Henrikh Mkhitaryan, Wayne Rooney, Juan Mata or Zlatan Ibrahimovic is likely to rigidly stick to his assigned attacking zone, for example.

Nonetheless, they are helpful for understanding United's general approach to play, and varied systems have made a notable difference to the Red Devils' style of play under Mourinho.

The season so far can be broken down into three phases—the initial 4-2-3-1, the switch to 4-3-3 and the recent experimentation, with a couple of exceptions to those rules.

Let's take a look at what Mourinho has done so far and speculate on how each formation could play into the rest of the season and beyond.