The Red Devils have turned their attentions to the 23-year-old after failing in their pursuit of Borussia Dortmund’s Jadon Sancho.
Dembele played little more than a bit-part role at the Nou Camp last season, making just nine appearances in all competitions as his campaign was blighted by injury.
The Frenchman’s stock has fallen at Barca since his 2017 transfer worth an initial £96.8m.
Question marks remain over the star’s attitude given his run-ins with Barcelona in the past over missed training sessions as well as punctuality.
He has even turned up late to training more than once since Ronald Koeman’s appointment as boss in the summer, with Marca reporting his latest misdemeanour on Monday.
Dembele did feature in Barca’s opening La Liga fixture at the weekend though, playing 20 minutes as a substitute of the 4-0 win over Villarreal.
Koeman appears to favour other players in Dembele’s position, and the Dutchman has left the player’s future up to him despite stating how pleased he has been with the forward.
Manchester United are looking to plot their path back to the top. Ole Gunnar Solskjaer has already brought in Donny van de Beek but Jadon Sancho remains Manchester United’s number one target.
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Discussing Dembele’s future, Koeman said on Tuesday: “I’m going to count on him, he was very good during the first weeks, he had a downturn last week.
“He trained well today and I’m counting on him. But these are the decisions of the club and the player.”
United are trying desperately to bring in reinforcements before Monday’s transfer deadline with Donny van de Beek currently their only summer addition.
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Already the club are facing problems with van de Beek’s agent though for using him as only a substitute thus far.
United did lodge a bid for Sancho worth an initial £73m, rising to up to £91.3m, but Dortmund were not interested in accepting less than their £108m valuation this late in the window.
The pursuit of Dembele now looks to be a stop-gap for United until they are in a position to get the Sancho deal over the line, which looks more likely to be next summer.
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