2. Rafael

Manchester United full-back Rafael may seem an unlikely and unfair choice for the loose cannon shortlist on the surface, but his tendency to lash out when frustrated and concede silly free-kicks means the Red Devils are always liable to be put under pressure with the Brazilian in the side.

Rafael was a prominent feature of United's march to the Premier League title last season but has failed to hit those heights so far this term, a nagging complaint that may seem minor until it comes back to haunt David Moyes' side.

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