Rampant Rovers destroyed last season's play-off finalists as two Junior Agogo goals gave Ian Atkins victory in his first match in charge of the Gas.
Agogo ran Mansfield ragged in a one-sided second half and only poor finishing denied the striker a deserved hat-trick.
Mansfield were unlucky to have goals ruled out in both halves and struck the woodwork through lively debutant Derek Asamoah late on, but rarely looked like earning a point.
It was one of Rovers' new boys Stuart Campbell who had the first chance, his deflected 18-yard drive well saved by the sprawling Kevin Pilkington.
Mansfield dominated the opening 20 minutes though the pace of Asamoah, Colin Larkin and Wayne Corden and had the ball in the net in the 13th minute, only for Asamoah's tap in to be ruled offside.
Asamoah again caused problems in the 23rd minute when his deft flick was only held at the second attempt by Kevin Miller.
The save proved vital as Rovers gained control of the match. Campbell, Jamie Forrester both shot wide from long range and then Forrestor was denied a breakthrough at the end of a sweeping cross field move by Dave Artell's last-ditch tackle.
Another sweeping move ended with Rovers taking a 30th minute lead. Agogo broke from a Mansfield free-kick deep inside his own half and released Ali Gibb on the right wing before racing into the area to convert the final cross.
Larkin twice went close to an equaliser either side of half-time. First Miller beat away his close range piledriver and then his curling drive brushed the outside of the post.
Four minutes into the second half the game was over when Gibbs again raced clear and crossed from the right for Agogo to tap in.
Agogo squandered several chances to complete his hat-trick, but Mansfield knew it was not their day when Asamoah hit the bar and then Artell had a goal ruled out for pushing.