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Has Rafael reverted to type?
The young Brazilian is arguably United's player of the season so far. He has grown in maturity and is truly beginning to blossom in his fifth season for the Reds.
However, he was visibly uncomfortable against Reading, and his fatal flaws were once again exposed.
Rash in the challenge and lacking in positional understanding, Rafael was booked early on and was unceremoniously hauled off to be replaced by Chris Smalling, who returned some order to the right side of defence.
Some have argued he was a scapegoat for far worse defensive performances by Rio Ferdinand and Jonny Evans at the heart of the back four. But Rafael's place was not under threat all season, and that has now changed.
The return from injury of both Smalling and Phil Jones raises the question of who is United's best option at right-back. All three players have different qualities to bring to the table, but following the embarrassing inability to defend set-peices over the weekend, Sir Alex may opt for additional aerial prowess.
Only three clean sheets from 15 league games have been achieved this season, and the apparent hoodoo of conceding the first goal in 10 of those fixtures is causing serious concern in the corridors of Old Trafford.
Maybe a change is necessary.
That said, a settled back four is a desirable axis upon which to build a solid defence, and maybe the biggest game of the season requires a constant, at least from the start.