Jason Kennedy's late goal for Rochdale meant Port Vale must wait at least another game to guarantee promotion.
Liam Chilvers put the ball in his own net to give Dale the lead but top scorer Tom Pope levelled with a close-range header.
Chilvers made amends for his earlier mistake and nodded home in the 89th minute to put the visitors ahead.
But Kennedy's header deep in stoppage time earned Rochdale a point and put Vale's celebrations on hold.
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