The visitors looked to be heading towards a shock win when Memphis Depay missed a 76th-minute penalty after Robert Braber open the scoring with half an hour gone on Saturday.
But pacesetters PSV showed their character with a late fightback, which began with substitute Jurgen Locadia fired past Kostas Lamprou in the Willem II goal from 20 yards with six minutes to go.
Three minutes later, Depay – who has now missed four of his last six Eredivisie penalties – atoned for his spot-kick failure, smashing a half-volley in despite the best efforts of Lamprou, meaning Ajax go into Sunday's clash against Heracles nine points behind Phillip Cocu's men.
Twente moved up to fourth place with a 2-1 win over Cambuur in the day's late kick-off, claiming all three points in the final stages of the game.
Renato Tapia put the hosts ahead just before the hour mark, but Martijn Barto appeared to have rescued a point for Cambuur 17 minutes from time.
However, Kyle Ebecilio struck in the third minute of stoppage time, stabbing beyond Leonard Nienhuis after latching on to Andreas Bjelland's knockdown.
As a result, Groningen moved above Cambuur in the race to clinch a UEFA Europa League play-off spot after claiming a 2-0 triumph at home to Go Ahead Eagles.
Albert Rusnak gave them a ninth-minute lead when his crossed deceived goalkeeper Mickey van der Hart and Tjarron Chery secured all three points in the second half, firing home after combining brilliantly with Jarchinio Antonia on the edge of the penalty area.
The day's other contest saw second-bottom NAC Breda claim a goalless draw at Excelsior.
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