Arsenal’s Chile striker was left out of the squad for their shocking 2-1 defeat at Bournemouth and Gunners manager Arsene Wenger admitted he expected the deal to be completed imminently.
United have edged ahead of rivals Manchester City in the bidding for Sanchez, being prepared to match Arsenal’s £35million valuation this month, with Henrikh Mkhitaryan possibly going the other way as part of the deal.
City had told Sanchez that if he came in the summer, as a free agent when his contract runs out, his potential wages at the Etihad could be doubled – but United are prepared to move now.
Wenger, who insisted that he would be given the cash to replace Sanchez in this transfer window, said: “Alexis did not refuse to play. He would have played but it’s a difficult period for him.
“He’s always been committed until now but he could have moved yesterday, today or not. It will be decided in the next 48 hours.
“It was difficult for him because he was on stand-by. That’s why I decided not play him.
“If Sanchez goes we need to replace him. If players like him go, we have to respond.
“At the moment, it’s the transfer period and in this kind of period, you try to use players who are completely focused on being at the club. It could happen today, tomorrow or not at all.
“I have been assured that Alexis will be replaced but there’s nothing concrete there yet.”
Arsenal’s other main target is Bordeaux’s Brazilian winger Malcom – for whom a £35m deal is close – with the player’s representatives in London yesterday.
The Gunners’ dismal defeat at the Vitality Stadium meant they have now gone five games without a win and are eight points off the top four.
Wenger said: “We made two very surprising mistakes. It was a lack of decision-making. We haven’t created enough. We looked lacklustre in the final third, not sharp enough. Of course it’s frustrating.”
Cherries manager Eddie Howe said: “The danger is that this win makes people think we can relax. We have to keep this momentum.”
Meanwhile Pep Guardiola admits he in unsure of what’s happening in the Sanchez saga.
He said: “He’s an Arsenal player. We have the squad we have. I don’t know what’s going to happen in this transfer window.”