Feyenoord's slim title hopes suffered a telling blow as they slipped to a home defeat against ADO Den Haag.
ADO are struggling to avoid the drop, but the gulf between the two sides was shrunk as the visitors claimed the spoils.
Finnish star Joonas Kolkka proved the scourge of Feyenoord, as he netted on 37 and 67 minutes to seal a vital three points for ADO.
Kolkka's first was a stinging drive, while the second which knocked the stuffing out of Feyenoord was a close range finish.
With PSV Eindhoven winning on Saturday, Feyenoord find themselves 13 points adrift of the league leaders.
Feyenoord's defeat let in AZ Alkmaar to cement their spot in second as a Haris Medunjanin strike handed them a 1-0 win at RKC Waalwijk.
Klaas Jan Huntelaar handed Ajax an early lead against NAC Breda, but they were pegged back by David Mendes da Silva's goal ten minutes from time.
Marc-Antonie Fortune popped up with a last minute winner for Utrecht at home to Heracles.