Arsenal are reportedly happy with the addition of Henrikh Mkhitaryan in the deal, and the £20 million fee seems enough for a player who would end up leaving for free in the summer.
The rivalry with City, Sanchez's goalscoring record in the Premier League - 60 in 122 games - and the fact the fabled No.7 shirt is vacant at United all conspire to make the prospect of this deal irresistible to many Red Devils fans.
Manchester City and Liverpool are also in the race for Sanchez but United have the upper hand because they're prepared to meet Arsenal's demands.
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In the tweet below, Ferdinand explains that he would love to see Sanchez join United and that he will personally direct the Chilean to Old Trafford to help push a move. United boss Jose Mourinho - as of recent - has been plotting to intercept the Sanchez move, as the issue of whether he signs in January or in the summer is yet to be determined.
"He's being vague, we have left him at home because of the situation", Wenger told Sky Sports.
Jose Mourinho said on Friday: "Sanchez is an Arsenal player, I don't know but probably this weekend he is going to defend Arsenal colours so I don't think it's correct to say things about Alexis Sanchez".
"I honestly believe Mkhitaryan is one of the best players in the Premier League, his confidence is just shot at United". But in relation to Alexis Sanchez I don't say a word.
It is hard to envisage Sanchez staying beyond January, but Arsenal will not sell him unless they can bring in a replacement, with a £35m bid for 20-year-old Malcom expected this week.