PSV extended their advantage at the top to 13 points with a 3-1 home win over PEC Zwolle on Friday, meaning Ajax required victory to take their ailing title defence into the final four matchweeks.
Despite a largely laboured first-half display, Frank de Boer’s team upheld their side of the bargain after Kolbeinn Sigthorsson converted a rebound when Ricardo van Rhijn's free-kick was parried.
Lucas Andersen curled home a sumptuous second with four minutes remaining to seal the points and ensure Ajax held onto their crown for at least one more week.
At the other end of the table, third-bottom NAC Breda spurned a two-goal lead to draw 2-2 with basement boys Dordrecht.
NAC appeared set to move out of the relegation play-off places thanks to a first-half brace from midfielder Adnane Tighadouini.
But Dordrecht scored twice in the space of three minutes as Giovanni Korte headed in a corner and Everon Pisas took advantage of some haphazard defending to smash a 69th-minute equaliser.
Nevertheless, three points were truly what the battling visitors required as they lie seven points adrift.
Heerenveen were the day's big winners, handing out a 5-2 beating to AZ Alkmaar despite falling behind to a first-minute strike from Steven Berghuis.
Another Berghuis goal levelled proceedings at 2-2 in the second half, but Heerenveen ran riot with three goals in the final 14 minutes as Sam Larsson notched a brace of his own.
Vitesse capitalised on that result by winning 3-1 at Excelsior to edge up to fourth.
Bertrand Traore scored either side of Tom van Weert's goal for the hosts and Renato Ibarra settled matters in stoppage time.
