Real Madrid have asked to be kept informed of three Manchester United players' movements ahead of the summer transfer window.
It is understood Madrid have reiterated their interest in David de Gea and are also monitoring Paul Pogba and Anthony Martial's situations.
Gareth Bale is believed to be among the players Real have offered United first refusal on as both clubs prepare to freshen up their squads.
Real are mindful of United’s long-standing admiration for Bale and desire to preferably sign two central midfielders ahead of next season.
They have intimated they could be amenable to offering Luka Modric or Toni Kroos, two players whom United have considered signing in the past, in a de facto swap deal.
Despite the obvious temptations, United are unlikely to entertain the prospect of negotiating with Madrid as they prioritize a new contract for De Gea.
De Gea's current contract expires next year but United have the option of extending it until 2020.
Bale's stock at Real has dwindled in another injury-plagued season and he was omitted from the starting line-up in their 3-0 Champions League defeat of Juventus on Tuesday night.
Mourinho has repeatedly stressed he does not want to make any attacking additions in the summer but could make an exception for Bale after he publicly courted the Welshman last August.
United first attempted to sign Bale from Southampton in 2007 and outbid Real in 2013.
United are believed to want to sign two central midfielders as they prepare to lose Michael Carrick and Marouane Fellaini at the end of the season.
Kroos and Modric remain two of the finest in their position but Real have no intention of discarding both players.
Kroos, 28, is contracted to Real until 2022 but the 32-year-old Modric's deal expires in 2020.
Mourinho brought Modric to Real in 2012 after Ferguson balked at the prospect of negotiating with Tottenham chairman Daniel Levy for the Croat the previous year.
Ferguson later remarked that dealing with Levy was 'more painful than my hip replacement'.
David Moyes worked on a deal for Kroos in 2014 but his sacking jeopardized the protracted transfer and replacement Louis van Gaal vetoed a move for the Germany international.
Real and United’s relationship is more cordial following the fall-out from the Cristiano Ronaldo transfer in 2009 when Sir Alex Ferguson became so incensed by the Spaniards' tactics he vowed he 'wouldn’t sell that mob a virus'.
United bought Angel di Maria from Real in 2014 and the clubs were working on a deal involving goalkeepers De Ge and Keylor Navas until the swap collapsed on deadline day in Spain in 2015.
Last year, United dealt with Real for Alvaro Morata but could not come to an 'economic agreement' and ended talks after it emerged their principal number nine target Romelu Lukaku preferred to join United over Chelsea.