Eredivisie Wrap: Vitesse held to draw by Heracles
With Twente claiming just a single point at RKC Waalwijk on Friday night, Vitesse - managed by former Heracles chief Peter Bosz - had the chance to go five clear.
However, they have now opened the door for Ajax, who can take over as league leaders by beating Roda JC on Sunday.
Vitesse made a positive start at Polman Stadion, Patrick van Aanholt scoring after six minutes and Lucas Piazon adding a second four minutes before the interval.
However, Bryan Linssen scored twice in the second half to salvage a share of the spoils for Heracles, who lie 12th.
Feyenoord maintained the pressure on the leading trio with a 3-0 win against Zwolle.
Lex Immers scored two goals in six first-half minutes to put Feyenoord firmly in control of the tie, with Jean-Paul Boetius adding a third after the break.
Feyenoord are now just four points behind Vitesse.
Goals were not in short supply as Heerenveen recorded a thumping 5-1 win at AZ.
Bilal Basacikoglu set the ball rolling for the visitors in the 12th minute, before Hakim Ziyech doubled the advantage nine minutes later.
Aron Johannsson pulled one back before the break, but further goals from Luciano Slagveer, Alfred Finnbogason and Ziyech consigned AZ to a fourth consecutive defeat.
In the day's other match, NAC Breda pulled away from the relegation play-off zone with a 1-0 win over struggling Cambuur.
Anouar Hadouir curled home the decisive strike for NAC in the 74th minute.