Riechedly Bazoer scored the winner 20 minutes from time to take Ajax clear of champions PSV Eindhoven who are second after beating PEC Zwolle 3-2 on Saturday.
Feyenoord dropped to third spot, five points off the pace, after throwing away a halftime lead to go down 3-1 at NEC Nijmegen.
ADO Den Haag crushed Heerenveen 4-0 while second from bottom SC Cambuur, who last weekend won their first league game of the season, made it two in a row with a 4-1 triumph at Excelsior Rotterdam.
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Sunday's other game saw Willem II Tilburg beat Roda JC Kerkrade 3-2.
In Amsterdam, Polish international Arek Milik gave Ajax the lead after 26 minutes before visiting De Graafschap equalised in the 38th through Kristopher Vida.
Bazoer's volley then made sure Ajax ended 2015 as 'winter champions'.
A goalkeeping error by NEC's Marco van Duin allowed Tonny Vilhena’s free kick to sail past him for Feyenoord's goal in the 20th minute.
The home team came out for the second half less inhibited, though, scoring twice in a five-minute spell around the hour mark thanks to Janio Bikel and Anthony Limbombe.
A counter attack five minutes from the end, as Feyenoord pushed forward in search of an equaliser, led to Christian Santos adding a third for NEC.
Aaron Meijers, Danny Bakker, Tom Beugelsdijk and Kevin Jansen were on target as visiting Den Haag eased past Heerenveen.
Nigerian striker Bartholomew Ogbeche netted twice while Jack Byrne and Jamiro Monteiro also struck as Cambuur swept aside Excelsior.
Willem II extended their unbeaten run to five league games by beating Roda JC, Dries Wuytens scoring twice. The league resumes on Jan. 15 after a break.
(Reporting by Mark Gleeson; Editing by Tony Jimenez; mark.gleeson@thomsonreuters.com; +27828257807; Reuters Messaging: Reuters Messaging: mark.gleeson.thomsonreuters.com@reuters.net)
