Chesterfield slumped to their third-straight defeat despite a second-half fightback as they lost 3-2 to Yeovil Town at the Proact Stadium.
The visitors took a two-goal lead but that was cancelled out in the second half before James Bailey's 90th-minute header clinched all three points.
Chesterfield trailed when a long ball found Olufela Olohola, who was given too much space to drive a low shot past Joe Anyon from the edge of the box in the third minute.
Three minutes later, the home side had Zak Jules carried off on a stretcher and Yeovil made it two in the 26th minute when Otis Khan cut in from the left too easily and beat Anyon with a shot from 20 yards.
But Chesterfield were back in it five minutes after the break.
Chris O'Grady whipped in a low cross that Robbie Weir flicked into the bottom corner and then the hosts levelled in the 72nd minute when Dennis scored from 30 yards with a superb lob.
But Yeovil stunned the home side in the final minute when Sam Surridge crossed and Bailey arrived at the back post to head home.