PSV Eindhoven were the chief winners on Sunday, as nearest pursuers Ajax and AZ Alkmaar played out a 2-2 draw in Amsterdam.
The champions ran out 2-0 winners at Groningen on Saturday to heap the pressure on the chasing pack.
AZ made the trip to Ajax on the back of a win over Excelsior, but they slipped behind in Amsterdam as Johnny Heitinga fired the home side ahead on 35 minutes.
Shota Arveladze drew AZ level on 51 minutes and they turned the game around shortly afterwards as David Mendes da Silva fired them in front.
Ajax have a striker of real quality on their books and Klaas Jan Huntelaar earned the home side a point with a header from George Ogararu's cross with 15 minutes remaining.
Feyenoord continued their push for a European place with a 3-1 win over ADO Den Haag.
All the goals came in the second half, with Nicky Hofs opening the scoring on 55 minutes.
Jonathan de Guzman made it two shortly afterwards and a penalty from Angelos Charisteas made the game safe.
ADO are in real trouble at the foot of the table and they only had a consolation penalty from Santi Kolk to show from their trip to Rotterdam.
Feyenoord briefly climbed to fourth, but they were overhauled by Twente who ran out 3-1 winners at Willem II.
Blaise N'Kufo was the hero for Twente as he netted a hat-trick, with his treble cancelling out Kevin Bobson's strike.
Vitesse Arnhem came from behind to beat RKC Waalwijk 3-1.
Jordan Remacle put RKC in the ascendancy, but goals from Danko Lazovic, Mads Junker and Youssouf Hersi secured the points for Vitesse.