Celtic suffered another title blip as goals from Chris Humphrey and Michael Higdon handed Motherwell their first win in five over the league leaders and moved them into second place in the Scottish Premier League.
Georgios Samaras had momentarily levelled matters following Humprey’s first-half opener, only for Higdon to put Stuart McCall’s side back in front and leave Celtic dropping points away from home for the second midweek in a row.
The home side made two changes from the side that fell to defeat at Ross County, with Stuart Carswell and Zaine Francis-Angol dropping out to be replaced by Steven Hammell and James McFadden.
Neil Lennon once again rotated his squad with Efe Ambrose, Kelvin Wilson, Joe Ledley, Dylan McGeouch and Gary Hooper all missing out on a start and Adam Matthews, Thomas Rogic, Kris Commons, Samaras and Victor Wanyama coming in.
The game started in an open manner, with Nicky Law sending a free kick wide for the home side and Commons’s goal-bound effort blocked by Adam Cummins after fine work from Beram Kayal.
Celtic were nearly gifted the breakthrough when Shaun Hutchinson failed to deal with James Morrison’s cross from the right and saw the ball rebound off his standing leg, but Darren Randolph managed to save.
But Motherwell regained their composure and hit first when they exploited the makeshift Celtic defence, with Law twisting inside the box before hitting a shot towards the back post, which Humphrey darted onto and smashed into the roof of the net for a half-time lead.
As the visitors went forward in the second half, Commons cut in from the right wing and unleashed a strike which curled round a Motherwell defender, but Randolph managed to get behind the ball to save.
The Scotland international had another chance a minute later as Anthony Stokes put him one-on-one with the keeper, but Randolph managed to push Commons wide and conceded a corner.
The equaliser finally came as Stokes played the ball to Forrest wide on the right-hand side and the winger crossed to the near post for Samaras, who got in front of Hutchinson and Randolph to head home.
Against the run of play Motherwell retook the lead as Hammell played in Law on the left and his cross found Higdon at the back post and the striker, who was left unmarked had the simplest of chances to tap home.
Celtic continued to push forward for the reminder of the game, with Ledley and Samaras having chances, but neither could get the Hoops back into the game as fell to their third defeat of the season.