Ajax cashed in fully after Heerenveen goalkeeper Brian Vandenbussche saw red after just three minutes for hauling down De Jong.

Theo Janssen converted the spot kick and, after Ismail Aissati scored the second, De Jong bagged his hat-trick to seal a ninth successive league win.

It was also a fifth clean sheet on the spin for Ajax as their lead at the top grew thanks to a 2-2 draw between closest rivals AZ Alkmaar and FC Twente.

Substitute Emir Bajrami snatched a last-gasp equaliser for Twente to ensure their clash at fellow Eredivisie title contenders AZ finished all square.

Jozy Altidore twice put the hosts ahead at AFAS Stadion but Luuk de Jong cancelled out the early opener before Bajrami's late heroics nicked a point for the visitors.

The draw - between the sides who were second and third in the standings, respectively, at kick-off - means Ajax have a three point lead at the helm.

Setback

PSV Eindhoven's title bid suffered a huge setback as second-half goals from Sander Duits and Mitchell Schet gave RKC Waalwijk a shock 2-1 win at Mandemakers Stadium.

Jan Vennegoor of Hesselink grabbed a late consolation for the visitors, but it was not enough to prevent Phillip Cocu's men finishing the evening seven points adrift of leaders Ajax.

The result was equally crucial for the hosts, who boosted their chances of reaching the play-off places for a slot in next season's UEFA Europa League by moving level on points with eighth-placed NEC Nijmegen.

Feyenoord dropped points in their push for automatic qualification for the UEFA Champions League after they drew a blank against Roda JC in their Eredivisie match at the Parkstad Limburg Stadion.

The Rotterdam-based club missed the chance to overhaul third-placed FC Twente and close the gap on AZ Alkmaar and Ajax in a game with few clear-cut chances.

NAC Breda remain just five points above the Eredivisie relegation zone after losing 2-1 at home to Heracles Almelo.

The home side took the lead just before the interval through Jordy Buijs, but conceded twice in six second-half minutes to the dismay of the majority of a 17,000-strong crowd.