Ajax lost further ground on leaders PSV Eindhoven when slipping to defeat at Vitesse Arnhem on Sunday.
PSV threw down the gauntlet when drubbing Willem II on Saturday, but Ajax were unable to respond.
Things started so well for Ajax as they raced into a two-goal lead through Zdenek Grygera and Tom de Mul.
However, they hit the self-destruct button in the second half and Vitesse punished them with a four-goal salvo.
Danko Lazovic started the fightback on 49 minutes and Vitesse were level shortly afterwards as Mads Junker hit the target.
The game seemed set to end in a draw, but two goals in the last minute from Fred Benson and Youssouf Hersi sealed an amazing win for Vitesse.
AZ Alkmaar also failed to make inroads on PSV as they were held at home by NEC Nijmegen.
RKC Waalwijk and Utrecht played out a 1-1 draw, with a goal from Tom Caluwe cancelling out an early strike from Robert Fuchs.
Roda JC climbed into the top half of the table with a 2-0 win over high-flying Twente.
Dieter van Tornhout was the man to provide the Kerkrade Crew with some Christmas Eve cheer as he netted a brace to seal the three points.