Modric, 27, scored a wonder goal to rescue Real when the two sides met in the Champions League second leg at Old trafford last week.
The former Tottenham star is still interested in playing at 'home' in the Premier League with United ready to renew their interest in the Croatia international.
Modric has failed to find his dazzling form with Real since making his £33million move last summer and was voted as the worst signing of the season in La Liga.
The former Spurs start was heavily linked to United prior to his move to Real as Sir Alex Ferguson tried to replace Paul Scholes. Modric has struggled to find first-team chances under Jose Mourinho and after the trip to Old Trafford, the Croatian is keen to make a future switch to Old Trafford.
United signed Shinji Kagawa in the summer after losing out on Modric, but there could be a possibility of signing him. Paul Scholes is likely to end his career in the summer while Ryan Giggs ha another year left on his contract. Wayne Rooney will be targetted by PSG and Bayern Munich at the end of the season.