Ajax let a two-goal lead slip and then came from behind to earn a thrilling 3-3 draw at Heerenveen.
The result leaves last season's title winners two points behind leaders PSV Eindhoven, who have nine from their first three games and visit Heracles Almelo on Saturday.
Niklas Moisander and Kolbeinn Sigthorsson put Ajax 2-0 up inside 17 minutes but by halftime they were behind as a double from Iceland forward Alfred Finnbogason and another goal just before the break from Magnus Eikrem put the hosts ahead.
Ajax's Denmark midfielder Eriksen, heavily linked with a move away in the transfer window, scored 20 minutes into the second period to earn a point for the Amsterdam side.
Ajax won a record 32nd league title last season and have now taken seven points from 12 at the start of the new campaign.