Mansfield caught Port Vale unprepared right from the start and took the lead inside the first minute.
Former Valiants player Wayne Corden broke from the halfway line and fought his way to the right side of the box where he unleashed a drive that hit Liam Burns and cannoned into Mark Goodlad's bottom left-hand corner after just 28 seconds.
After a frustrating opening, relief came for Vale in the 30th minute when Phil Charnock's corner was whipped into the Mansfield box, and Michael Cummins headed it perfectly inside Kevin Pilkington's right post.
The Valiants doubled their tally in the 33rd minute when a long ball to Billy Paynter from John Durnin was turned on well and he got to the byline before crossing for Cummins to hammer home his second.
Mansfield seemed to offer little more after their early goal and with Vale firing on all cylinders towards the end of the half, the Stags would have to try for damage limitation.
Never far from the action Cummins set up the third goal when a cross from the right missed everybody until Ian Armstrong dived to send the ball just inside Pilkington's right post in the 50th minute.
Vale were still hungry for goals and in the 66th minute another killer ball from Cummins sliced open the Mansfield defence and sent Paynter clear and he fired his ten-yard shot home.
Mansfield replied a minute later with a brilliant individual effort from Isyeden Christie.
After the game Vale boss Brian Horton said: "Credit to us considering we went 1-0 down after 30 seconds.
"I thought we stuck with it and the fans stayed with us.
"It was a good game all round and we're pleased with the three points."