Yeovil's joy at their first win in seven matches was over shadowed though by two series injuries.
Teenager Anthony Barry dislocated his knee and was taken to hospital after falling awkwardly when making a 42th minute clearance.
By then the Glovers had already lost debutant midfielder Tom Doherty who suffered a leg injury after just eleven minutes.
Doherty went down after his first tackle and is believed to have suffered after a broken leg from which he had just recovered.
Yeovil were always on top and should have gone in front in the 17th minute. Matt Harrold headed wide over an empty net.
Eight minutes later Chesterfield produced their first clear cut of chance of the game when Derek Niven struck a powerful shot from 20 yards which Chris Weale could only push away. As Paul Hall moved in for the kill the Yeovil keeper managed to grab the ball into the second attempt.
Harold missed an easy chance before setting up the opening goal eight minutes before half time. The lanky striker headed on a long clearance and Davies put a shot into the bottom corner. Giving Carl Muggleton no chance. Muggleton saved Chesterfield in the 55th minute when he pushed out the goal-bound shot from David Poole.
Chesterfield came increasingly desperate switching to a 4-4-2 formation but still lacked any penetration.
They went close in the 69th minute when substitute Adam Smith turned outside the box before firing in a shot which flew over the bar.
Chesterfield's misery was compounded in stoppage time when they conceded two more goals. Poole ran at the home defence before laying on a faster Harold, the striker could have shot himself but instead passed the ball to Davies who blasted in from 15 yards.
In the fifth minute of time added on Chesterfield's defence gave the ball away under no pressure at all, Paul Terry crossed into the box although his first effort was cleared he put the ball back in and they converted it from close range.