Ajax Amsterdam needed until late to take distance from Heracles Almelo, but eventually beat their opponents 0-3 to remain at two points from leaders AZ.
Martin Jol's men struggled for over an hour at Almelo's Polman Stadium, but broke through their own misery in the 68th minute when Demy de Zeeuw's corner kick was headed home by Toby Alderweireld.
Things got worse for Heracles when Quansah conceded a red card two minutes later, leaving Ajax with more space to add a second goal.
This goal came in the 87th minute. Luis Suarez reached Dario Cvitanich, who easily nodded in from close range. Two minutes later, Ismail Aissati's curled shot set the score to 0-3.
Ajax are now in sixth position, while Heracles remain in ninth.