With Mo Salah forced off after a controversial challenge from Sergio Ramos, van Dijk says that Real Madrid's men flooded down their left flank.
"Mentally, something changed for Real Madrid once Salah left the pitch," Van Dijk told 'De Telegraaf'.
"Suddenly Marcelo, Benzema and Ronaldo all ganged up against our young right-back Trent Alexander-Arnold and left the whole right flank free.
"With Salah, they would not have dared."
Real went onto win the game 3-1, with goals from Karim Benzema and Gareth Bale enough to secure the trophy for the third year running.