Totally outplayed in the first half, a triple substitution at the break revitalised Rangers and completely changed the momentum of the match.
Within minutes of the restart, Chermiti coolly curled in, before the Portugal under-21 international headed a cross off team-mate Raskin to rouse Ibrox further.
Rangers piled forward looking for the win but couldn't find a third and were finally undone by Longelo after yet another Motherwell counter-attack.
This was a sensational return to form for Jens Berthel-Askou's side, who put their recent run of four defeats and a draw firmly behind them with a mesmerising display full of bravery, movement and fast-flowing football.
They completely outplayed their hosts and it was no surprise at all when they took the lead. A lovely move was given the finish it deserved when Stephen O'Donnell's pass into the area was perfectly slotted home by Fadinger.
If the Ibrox crowd were stunned by that, worse was to follow when, after another fine move, a wonderful cross from Tom Sparrow was met by a perfect first-time finish by Longelo.
For a team in the midst of a three-way title fight - and playing at home - Rangers offered surprisingly little.
But Rohl made his intentions clear with a triple-substitution - Mikey Moore, James Tavernier and Mohamed Diomande replacing Bojan Miovski, Jayden Meghoma and Tochi Chukwuani.
There was nearly an instant impact when Djeidi Gassama's cross clipped the top of the bar, and momentum did change as Rangers pulled themselves level.
But Motherwell weathered the storm and pressed forward to snatch a winner. They remain fourth and have given their hopes of European football a shot in the arm.