Real Madrid have endured a difficult start to the season, with the currentl La Liga champions already eight points behind Barcelona at the summit.
Modric’s form has been called into question with the 32-year-old struggling to find his best form.
Alli, meanwhile, has helped Tottenham overcome their Wembley woes to sit third in the Premier League table, behind only Manchester City and Manchester United.
And Spanish website Don Balon claims Real Madrid boss Zidane has earmarked the England international as a replacement for Modric come the end of the season.
Alli’s rise to the top was completed last month.
The 21-year-old produced a stunning display to fire Tottenham to a 3-1 Champions League win over Real Madrid at Wembley.
However, with Spurs struggling to compete for major trophies, talk of a move away from north London has been rife.
And Don Balon say Zidane would love to bring him to the Bernabeu as Modric’s replacement.
The Frenchman was supposedly amazed at Alli’s performances against his side during their recent European showdown.
And he thinks that the England star could be a huge Real Madrid success if he were to make the move to Spain.
However, this has supposedly not sat well with Mateo Kovacic.
Kovacic resisted offers from Liverpool and Spurs to remain at the Bernabeu this summer.
But any move for Alli would likely see the Croatia international depart.