Ajax's six-match home league winning streak in the Eredivisie was ended as they were held to a 1-1 draw by Cambuur on Sunday.
Frank de Boer's side last dropped points at the Amsterdam Arena on November 2, scoring 17 goals and conceding just once in the meantime, but they were forced to settle for a point after being frustrated by Cambuur.
It appeared business as usual for the hosts when they went in front after just two minutes from Siem de Jong, but they failed to build on that advantage and were made to pay when Martijn Barto equalised eight minutes into the second half.
The draw leaves Ajax six points clear at the summit from Vitesse, who won 2-1 at NAC Breda 24 hours earlier.
Third-placed Twente missed out on the opportunity to join Vitesse on 52 points when they went down 1-0 at Go Ahead Eagles.
Jarchinio Antonia scored the only goal of the game in the 33rd minute to lift the home side to 12th place, four points clear of the bottom three.
The result put a huge dent in Twente's ever-slimming title hopes, and Marcel Jansen's men are imploding just at the wrong time with only one win in their past six league outings.
Feyenoord are a point behind them in fourth after a 2-0 win at Groningen.
Ruben Schaken opened the scoring after quarter of an hour before Stefan de Vrij doubled the lead four minutes into the second half to end Feyenoord's three-match winless run, while defeat for Groningen leaves them a point out of the UEFA Europa League play-off places.
Elsewhere, strugglers RKC Waalwijk and ADO Den Haag drew 1-1 in a result that does little to aid either side's bid to pull away from the drop zone.
Den Haag went in front on 17 minutes thanks to Roland Alberg but Romeo Castelen's equaliser three minutes before the interval ensures both teams remain firmly entrenched in the relegation scrap.