Alli has shone for Tottenham this season, leading the title for Mauricio Pochettino’s side along with star striker Harry Kane.
Alli has scored eight goals in his last seven games and netted Spurs’ first in their 2-2 comeback draw with Manchester City on Sunday.
Express Sport understands Real Madrid are prepared to trump all offers to sign the Tottenham playmaker.
Dele Alli is arguably Tottenham's best player
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Tottenham Hotspur are in the process of building a new 61,000 capacity stadium on the site of White Hart Lane, due to open at the start of the 2018/19 season
Real Madrid paid a then world-record £85million to land Gareth Bale from Spurs in 2013.
And while Real boss Zinedine Zidane now wants to raid Spurs again, Manchester United are said to ready to rival any move.
Lawyer and former FIFA registered agent Rodriguez, who used to work with super-agent Jorge Mendes at his company Gestifute, claims United want Alli.
“Manchester United have been vigorously scouting Dele Alli for 6 months. The club have ID'd him as their No.1 target. Spurs want £100m #mufc,” he tweeted.
Manchester United have been vigorously scouting Dele Alli for 6 months. The club have ID'd him as their No.1 target. Spurs want £100m #mufc
— Vincent Rodríguez (@VRodriguezlaw) January 24, 2017
Tottenham star Dele Alli is wanted by Real Madrid and Manchester United
Harry Kane says Tottenham team-mate Dele Alli is going nowhere
Alli and Kane, both England regulars, have proved to be an impressive double act for Spurs this season.
But Kane does not believe that his 20-year-old team-mate is looking to leave White Hart Lane.
“Dele is a fantastic player and Tottenham is the right place for him, even if so many want him," Kane said.
"We have a great future ahead and he is part of it, he has no reason to leave.”