No-one was more delighted than acting manager Steve Thompson. For the third time in his seven years he was asked to take control following Friday's departure of Gary Johnson to Bristol City.
Thompson saw his team come under the cosh in the first half and Vale felt they should have had the match tied up in that spell.
But once again their attack was firing blanks and it was left to skipper Sam Collins to move up from the back and come closest to getting the goal that has now eluded them for three games.
In the third minute, following a corner, Collins looped a 20-yard shot goalwards but the ball bounced to safety off the crossbar and in the 31st minute he fired in a shot that would almost certainly have beaten goalkeeper Chris Weale, but Efe Sodje made an instinctive clearance.
Yeovil came more into the picture in the second half but for the second successive match were reduced to 10 men by a red card.
In the 59th minute recent signing Alejandro Melono clattered into Nathan Lowndes on the halfway line and referee Trevor Parkes immediately got out his red card.
That decision seemed to galvanise the Glovers into action. A minute later a similar challenge saw another Yeovil player, Phil Jevons, shown a yellow card but tempers cooled and in the 84th minute Yeovil grabbed the winner.
Lee Johnson, who stayed behind when his manager father went to Bristol City, fed Kevin Amankwaah with a terrific pass inside a defender.
The speedy full-back, who had caused problems for Port Vale all afternoon, crossed from the right and Matt Harrold swept in the winner from the edge of the box.
It was the first league goal for the young substitute who had earlier replaced Pablo Bastianini.