Having won 2-1 in Amsterdam, Real hold the slender advantage but they will be without the inspirational captain Sergio Ramos who is serving a three-match suspension.
Los Blancos come into the game on the back of three consecutive home defeats - including two by Barcelona last week.
And amidst their current struggles, Modric conceded the exit of their club-record goalscorer to Juventus has affected their results this season.
The 34-year-old was top scorer in the past six Champions League seasons and Real's inability to replace the five-time Ballon d'Or winner have exposed the frailties of the Spanish giants.
Only three of their players have scored more than five goals this season - Karim Benzema (20), Gareth Bale (13) and centre-back Sergio Ramos (11).
However, their record in the Champions League has been remarkable, with Juve the last side to knock them out the competition in the 2014/15 semi-finals.
Real Madrid XI: Courtois, Carvajal, Varane, Nacho, Reguilon, Kroos,Modric, Casemiro, Lucas Vazquez, Vinicius Junior, Benzema
AFC Ajax XI: Onana, De Ligt, Van de Beek, Neres, Tadic, Mazraoui, Blind, Schone, F. de Jong, Ziyech, Tagliafico