PSV beat De Graafschap 4-2 on Saturday to go top on 50 points.
Roda substitute Maecky Ngombo scored three minutes into stoppage time to deal a serious blow to Ajax after they had gone 2-0 ahead inside the first half-hour.
Arek Milik headed home a corner and two minutes later Anwar El Ghazi punished Roda for losing possession as Ajax began strongly.
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Roda, however, pulled one back before halftime through Rydell Poepon and there was a dramatic finish as Ngombo scored from a corner.
It was Ajax's second successive draw and left them on 49 points.
Kevin Jansen and Gianni Zuiverloon scored for ADO Den Haag, who condemned Feyenoord, who remain third on 36 points, to a another setback.
"Our confidence is lost after all these losses," Feyenoord captain Dirk Kuyt told Dutch television.
Heerenveen won 1-0 in a derby at SC Cambuur, who remain second from bottom.
(Reporting by Mark Gleeson; Editing by Toby Davis)
