Pogba has not started a match for United since September after an injury-blighted season and is now recovering from ankle surgery as he bids to make himself available for selection for the first time since Boxing Day.
United have failed to extend Pogba's contract which ends in a year's time though there is the option to extend it by a year if needed.
Isco, 27, has struggled to hold down a regular spot in the first team at the Bernabeu this season, being limited to just 14 La Liga appearances and having scored just one goal.
Pogba spent four years in Turin after leaving Old Trafford in 2012 where he won four consecutive Serie A titles.
Lovren wants Liverpool to replicate Barca’s success Why?" City face Real in the first leg of their Round of 16 tie at the Bernabeu on February 26 with the return match on March 17. I dream and will enjoy preparing games games against madrid , to see what we can do.
Do you think Pogba will still be a United player next season?
"He'd like to come back to Juventus but we'll see what will happen after the Euros".
The Frenchman is a world-class midfielder and United should demand a massive transfer fee for him in case they decide to offload him permanently.
"Paul wants to play at the best level but he can't escape by Manchester United if they are in a hard situation", Raiola told reporters after Juventus drew 1-1 with AC Milan on Thursday.
Pogba had set his sights on a move to Madrid but Real's offer of £27.6m plus Colombia forward James Rodriguez got nowhere near United's £160m valuation.