Ousmane Dembele is one of four alternatives Manchester United are working on if they can't sign Jadon Sancho, along with Ismaila Sarr, Luka Jovic and Edinson Cavani.
Dortmund set United a deadline of August 10 to agree a deal for Sancho, and have stated on several occasions the winger will not be leaving now that date has passed.
United are keen to sign a winger during this transfer window and, while their first choice is Sancho, Dembele represents a strong alternative on a loan deal.
The 23-year-old was a club-record signing for Barcelona when he arrived from Borussia Dortmund for €105m (£95.75m) in August 2017.
Thirty-three-year-old free agent Cavani, Watford's 22-year-old Sarr and Real Madrid's Jovic, also 22, are also on United's list, with the aim of strengthening across the front line.
Manchester United have spent just £39m this summer - on Ajax midfielder Donny van de Beek - while Chelsea (£204.1m) and Man City (£147m) have been active in the transfer market. In fact, United have spent less than any big six side, bar Arsenal.
Sky Sports News reporter Dharmesh Sheth told The Transfer Show: "It is thought United are working on at least four alternatives to Sancho. While Cavani and Jovic aren't seen as like-for-like replacements, I think Manchester United's priority is to strengthen the depth of that forward line.
"With Cavani, Man Utd would have to take into account his wages and his age - he's 33 years old - and also the length of the contract he would want at this stage of his career. As for Jovic, the Real Madrid boss Zinedine Zidane won't rule out a departure. There are reports coming from Italy that he's been offered to Roma.
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"Then there is Sarr. If Manchester United fail to get Sancho, Cavani or Jovic, all is not lost because they can still buy Sarr until the domestic deadline on October 16 because Premier League clubs and EFL clubs can still do business after October 5 so they have another 11 days to maybe get a deal done.
"Manchester United's interest in Sarr can almost take a back seat, they can use it as a watching brief just now, unless someone else comes in for him, of course."
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Sancho misses Dortmund training, selected for England
Sancho was not present at Borussia Dortmund's training session on Thursday due to an ongoing illness, despite receiving a call up for Gareth Southgate's England squad the same afternoon.
Sancho did not drive into the Brackel training ground in North Rhine-Westphalia, as members of Lucien Favre's squad began to arrive for coronavirus testing from 12pm and for afternoon practice, which began at 3pm.
Sky Sports News has been told he is still suffering from the "respiratory infection" which prevented him from travelling with the team for Wednesday's German Supercup final against Bayern Munich.
This in turn will mean he is unlikely to play against Freiburg in the Bundesliga on Saturday, and it remains unclear whether he has been able to take a COVID-19 test at home or elsewhere.
Sancho was included in England's 30-man squad for matches against Wales, Belgium and Denmark.
England's players are due to report for international duty at St George's Park on October 5, which will coincide with transfer deadline day.
Borussia Dortmund continue to emphasise that Sancho will not be sold this window, while Manchester United are expected to table another bid for him this week, after their £91.3m (€100m) offer was rejected on Monday.
United legends: Club need to spend
Sky Sports' Gary Neville took to Twitter on Wednesday to bemoan Manchester United's lack of business so far this summer, insisting Solskjaer needs a centre-back, left-back and forward before Monday's deadline.
'Big six' summer spending
|2. Man City||£147m|
|5. Man Utd||£39m|
"It's appalling that in this market which is probably the easiest in PL history to get transfers done that United haven't done more yet ! They must get Ole a CB , LB and Forward pre deadline!
"The others are managing to get things over the line why not United !"
Asked by another Twitter user whether they would be panic buying several players this late in the window, Neville replied: "Panic Buy! They've needed these positions filling for 12 months , had a national lockdown to regroup and re-set and ample time to manoeuvre deals to a conclusion."
It’s appalling that in this market which is probably the easiest in PL history to get transfers done that United haven’t done more yet ! They must get Ole a CB , LB and Forward pre deadline! The others are managing to get things over the line why not United !— Gary Neville (@GNev2) September 30, 2020
On Monday Night Football, Roy Keane sees tough times ahead if United don't spent before Monday.
When asked if failure to finish in the top four could signal the end of the road for Solskjaer, Keane said: "Yeah, I think so. If you're the manager of Man Utd, and they can invest in the next week and buy one or two... if they don't invest in the next week, then it's tough days ahead.
"The remit will be different for Ole this year. I think last year, it was about getting into the top four - I know they got to three semi-finals - but it will be higher this year.
"They will certainly have to get a bit closer to Liverpool and Manchester City. The points total cannot be the same as it has been over the past three or four years.
"Ole will probably have to get his hands on a trophy. I think the honeymoon period is certainly over for Ole, and the pressure starts to mount now, particularly with the performances like that over the last week or so."
Former United midfielder Darren Fletcher has also called on the club to Solskjaer in the transfer market.
"We know it's more difficult for Manchester United to sign players. The value goes up, the negotiations are difficult," Fletcher told Sky Sports.
"But at the same time they will be frustrated - Ole, the fans, everybody around the club - by the fact that Chelsea and other teams can do their business early, and that other teams have spent a lot of money already while Manchester United look like they are going to leave it last minute.
"For Manchester United to get to where they want, they need players. They need three, four, five players to get anywhere close to challenging Liverpool. If they don't recruit, they are going to find it tough to finish top four.
"I would hate all that pressure and criticism to go on Ole Gunnar Solskjaer, because I feel he's done a fantastic job.
"The board have to back him. Ole will have identified targets and so will the club. They've got five or six days to get him some help and get him some players in."
Does Cavani go against United transfer policy?
South American football expert Tim Vickery:
"This is Cavani's last contract in Europe, and there are a lot of unanswered questions here on what he wants and what prospective clubs want. He's already priced himself out of Benfica where he would've been the main man in their attacks. So are his priorities sporting our financial?
"From the point of view of Manchester United - yes, they have been linked with him - but you would've thought that if they really wanted him, with no transfer fee to haggle over, why the delay? Why hasn't it happened?
"It would seem to fly in the face of United's current transfer policy in wanting hungry youth. Today, he's been linked in Spain with Atletico Madrid with Diego Costa potentially leaving to join Paris Saint-Germain.
"But do Atletico Madrid really want to pair Cavani with Luis Suarez? A kind of 'Dad's Army' veteran Uruguayan attack? We have more questions than answers. The one thing that we do know is that he does have options - so if it doesn't happen for him in this window, he can go back to South America. There's no lack of options even in Brazil and his native Uruguay with Nacional."
Summer transfer window - key dates and times
The summer transfer window closes at 11pm on Monday, October 5 with a feast of activity lined up on Transfer Deadline Day on Sky Sports News and across our Sky Sports platforms.
A domestic-only window for deals between the Premier League and EFL then runs from October 5 and closes on Friday, October 16 at 5pm. Follow all the news and analysis on SSN and across Sky Sports' digital platforms, including with our dedicated Transfer Centre blog.