Heerenveen denied Ajax the chance to go top of the Eredivisie as a late equaliser forced a 4-4 draw in Amsterdam.
Earlier on Sunday, PSV Eindhoven were held to a 2-2 draw at lowly Emmen, leaving the door open for Ajax to take first place if they triumphed against Heerenveen.
Dusan Tadic and Sam Lammers exchanged early goals, with the former Southampton midfielder making it 2-1 to Ajax, from a fine Daley Blind pass, in the 16th minute.
After Tadic missed a penalty, Pelle Van Amersfoort's own goal was cancelled out by Lammers in the 51st minute and 10th-placed Heerenveen drew level through Mitchell Van Bergen just before the hour.
Klaas-Jan Huntelaar - by sticking away a Tadic cross - looked to have won it for Ajax in the 83rd minute but Kik Pierie pounced at a corner to frustrate Erik Ten Hag's team.
Two late goals from substitute Nicklas Pedersen had seen PSV pegged back at Emmen.
Captain Luuk De Jong fired the leaders ahead with a 16th-minute header and they were two goals up when Angelino found the top corner after the break.
But Denmark's Pedersen, who entered the fray in the 78th minute, tucked away a Michael Chacon assist before scoring in stoppage time to deny PSV all three points.
Elsewhere, Fabian Serrarens scored a hat-trick as bottom side De Graafschap pulled off a shock 5-1 home victory over Fortuna Sittard.
He bagged a brace before half an hour was up and it was 3-0 before half-time as Youssef El Jebli got on the scoresheet. Ahmed Messaoudi replied for mid-table Fortuna, yet Serrarens and El Jebli both notched again to put the game to bed.
Willem II made it back-to-back wins as Pol Llonch and Marios Vrousai struck in a 2-0 success against 10-man NAC Breda, who had Mounir El Allouchi sent off.