Andy Halliday's late Scottish Premiership winner continued Motherwell's stunning start to the season as Hibernian head coach David Gray rued his side's wastefulness and branded his 10-man side "unprofessional".
After a goalless first period, during which Gray's men should have put themselves ahead at Easter Road, Apostolos Stamatelopoulos made the hosts pay for their profligacy by opening his Well account with a clinical near-post finish.
That goal sparked a manic second half as an inexplicable Stephen O'Donnell error then allowed Junior Hoilett to drive forward and curl in an equaliser just three minutes later.
But the Leith side should have been out of sight before they even needed to find a leveller - and they were then reduced to 10 when Nectar Triantis was shown a second yellow card for a late challenge on Tony Watt.
That drove Stuart Kettlewell's men on to find a winner, which they got when Kofi Balmer's long throw was met on the volley at close range by former Hearts midfielder Halliday, who celebrated wildly in front of the away support.
"It's very difficult to take," Gray told BBC Scotland. "It's clear, we can't dominate as much as we did and create the chances we did and not win the game.
"You can't not take those chances at this level. The set pieces in the second half - unprofessional. You need to see it through and defend your goal."
The away side, who remain fourth and move level on points with third-placed Rangers, have goalkeeper Aston Oxborough to thank for playing an integral role in earning a fifth win in six games.
Meanwhile, with just one victory from seven league matches, Hibs fans will remain unconvinced by their team amid a poor start to the campaign.