Calvin Andrew climbed highest in the depths of injury time to head home the only goal of the game and claim a fully deserved victory for the Dale.
Manager Keith Hill named three changes from the side which started against Preston North End with Jamie Jones, Joe Rafferty and Reuben Noble-Lazarus coming into the side in place of Josh Lillis, Scott Tanser and Joe Bunney. Second-year scholar James Hooper was handed a place on the bench.
Rafferty in his unfamiliar left-back position, showed no less desire to get forward. After picking up the ball midway into the Port Vale half he cut inside onto his stronger right foot and looked to find the top corner from all of 35 yards. It had the power but not the accuracy needed as it was comfortably collected by the goalkeeper.
The referee was forced to intervene as tempers flared after Rhys Bennett appeared to take Mark Marshall's high boot to the head. His cards stayed in his pocket however as he looked to settle things down. Michael Rose looked to drill the resulting free kick to the far post but it was deflected over the crossbar off the leg of a Port Vale defender.
As the first half drew to a close, Dale created the best opportunity of the half from another Michael Rose free kick. From the right of the box, he whipped the ball towards the near post where Vincenti got his head on the ball, but with a Vale defender all over him, he headed over the crossbar.
HALF TIME: Rochdale 0-0 Port Vale
Reuben Noble-Lazarus broke quickly down the left after poking the ball through the legs of the Vale right back. Upon getting to the edge of the box, he drilled a superb ball, dangerously across the face of goal but there was nobody there to poke the ball home.
Some quick interplay between Ian Henderson and Peter Vincenti allowed Henderson to break into the box. With his defender making life difficult for him though, the ball got away and at full stretch he could only poke a tame effort towards goal.
As Dale looked to find a winner, Keith Hill made three substitutions to change the shape and the emphasis of the side. Hery was replaced by Andrew, Noble-Lazarus by Logan and Cannon by Camps, and these changes had an obvious impact in shifting Dale up a gear to take total control.
With the game into the 95th minute, it was jubilation for Dale as Andrew rose far above the Port Vale defence to glance a header into the back of the net. With one last effort, the ball was pumped into the box from the right wing and Andrew leaped to direct a header across goal and all Chris Neal could do was watch the ball nestle into the bottom corner of his goal as Andrew wheeled away to celebrate with the fans.
FULL TIME: Rochdale 1-0 Port Vale
Man of the Match: Andy Cannon
REPORT BY ROB ANDERSON