Danny Johnson's late goal earned Motherwell a precious Scottish Premiership point and prevented Celtic returning to the top of the table.
Brendan Rodgers' side looked like returning to the summit thanks to Ryan Christie's sumptuous goal - his sixth in nine games - but they are now third.
Leigh Griffiths had a first-half spot-kick saved by Mark Gillespie and Filip Benkovic had an effort disallowed.
Johnston skidded a late shot past Craig Gordon to earn an unlikely draw.
Champions Celtic now trail Kilmarnock by a point - albeit with two games and hand - and are behind Rangers on goal difference.
On Saturday, Celtic host Kilmarnock, whose manager Steve Clarke has yet to lose to the Parkhead club in his spell at Rugby Park.
Motherwell, whose best chance before the goal was a Conor Sammon shot straight at Gordon, stay ninth - six points clear of the relegation play-off place.
Most of the discussion pre-match was on who had been left out of the Celtic team.
From Sunday's League Cup final win there were seven changes in total, including Odsonne Edouard, Tom Rogic and James Forrest all dropping out, with captain Scott Brown among those returning.
However, it did not take long into proceedings at a misty Fir Park for the headlines to turn to one man who is now an integral part of the Celtic team.
Sitting narrow on the left of midfield, Christie was unplayable at times, particularly early on as Motherwell - who lost captain Peter Hartley after six minutes to injury - were pushed deeper and deeper.
On 13 minutes, the man who won Rodgers his seventh trophy as Celtic manager at the weekend demonstrated his class.
With the hosts' defence a man light while Liam Donnelly was off receiving treatment, Christie gathered the ball in the Motherwell box with a neat first touch before a crisp finish across Gillespie arrowed into the far corner.
It was a game of few chances as Stephen Robinson's side were so focussed on repelling Celtic that they struggled to create opportunities of their own.
Ten minutes after taking the lead, Benkovic had the ball in the net and the large travelling support celebrated only for referee Kevin Clancy to rule it out for a tug in the box.
With half-time approaching, the home side could have fallen further behind.
Christie was again at the heart of it, with a rash challenge from Andy Rose bringing him down inside the penalty area. Griffiths stepped up, but Gillespie was equal to his spot kick, diving superbly to his left before then punching clear.
Motherwell emerged stronger in the second half and pushed back the Celtic tide.
An Allan Campbell shot straight at Gordon gave them hope before Sammon saw a low shot smothered by the Scotland keeper.
The chance looked to have gone for Motherwell but, in the dying seconds, with Celtic clinging on, they struck to claim a precious point.
The ball broke to Johnson on the left edge of the box, and with a swipe of his left foot, his shot evaded Gordon's grasp and hit the far post before ruffling the net.
BBC Scotland's Alasdair Lamont at Fir Park
Just as they did twice last season, Motherwell denied Celtic victory at Fir Park with a performance of guts and determination.
They refused to accept defeat and showed a resilience that earned them a similar result against Rangers and an emphatic win over Aberdeen. Robinson has bemoaned his side's inconsistency but they always turn up when the big teams come to Fir Park.
It looked like Celtic were on course to return to the top of the league and they played some good football in the first period, but after Griffiths missed the penalty they seldom tested Mark Gillespie.
Rodgers cut a frustrated figure at times on the touchline as his team failed to maintain the fluency they had in the early period and ultimately paid the price with Johnson's late equaliser.