Goals from Arkadiusz Milik, Riechedly Bazoer, Lasse Schone and Davy Klaassen gave the Amsterdam team a fifth straight victory and extended their unbeaten run to 10 league matches.
It saw Ajax move back to within a point of PSV after their 3-0 win at FC Groningen on Saturday, with the two Dutch giants set to clash at the Philips Stadion in a fortnight's time.
The battle for European places remains fierce after AZ Alkmaar, Feyenoord, Vitesse and NEC all won.
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A Derrick Luckassen strike and a Vincent Janssen penalty saw AZ defeat Excelsior 2-0, with the visitors having Sander Fischer sent off.
Jens Toornstra, Dirk Kuyt and Eljero Elia were on target for Feyenoord in a 3-1 home success against SC Cambuur Leeuwarden, who had drawn level at 1-1 through Martijn Barto.
An injury-time goal from Zhang Yuning saw Vitesse take all three points with a 2-1 victory at Roda JC. Isaiah Brown put Vitesse ahead but Mike van Duinen equalised for the hosts before the late drama.
Christian Santos' late effort gave NEC a 1-0 home win against Heracles Almelo.
