Ajax maintained their three-point advantage over Feyenoord with a 1-1 away draw on Sunday, as PSV Eindhoven jumped into second spot.
Feyenoord lost ground in the Eredivisie title race after a shock 1-0 loss against ADO Den Haag.
There were Eredivisie wins for both Ajax and PSV on Saturday, while second-placed Heracles slipped to defeat.
Heracles Almelo moved to the top of the Dutch league with a 2-1 win over champions PSV Eindhoven at the Polman Stadion on Saturday.
Wout Weghorst scored the only goal as high-flying Heracles beat ADO Den Haag 1-0 to climb to second in the Eredivisie.
Feyenoord and Roda JC secured opening day victories in the Eredivisie.