The game started in an open and entertaining fashion and, after David Clarkson and Derek Riordan had sent shots over the bar for either side, Kenny Miller had a great chance to open the scoring for Celtic.
A long ball over the top saw him get on the wrong side of Mark Reynolds only to then shoot tamely wide.
After the early exchanges, the game deteriorated into a tame affair with neither side showing any great urgency. Motherwell played some nice football without having a cutting edge while Celtic created a couple of half-chances that Miller and Riordan should have converted.
Riordan broke the deadlock ten minutes before the break when he was on hand to convert a rebound following Graeme Smith's fine save from Shunsuke Nakamura's 20-yard shot, after the Japanese midfielder had created his own space to make the effort possible.
The Steelmen almost equalised three minutes later when Artur Boruc was forced to make two outstanding saves, firstly from Clarkson and then from Richie Foran's volley from the rebound.
Boruc was to prove to be Well's nemesis at the start of the second half as well when he made two outstanding saves in the opening 15 minutes, firstly point-blank from Scott McDonald who had been released by Clarkson.
McDonald returned the favour setting up Clarkson, but again Boruc stood up well to make the save.
Celtic introduced Craig Beattie to the fray and he made an instant difference as he sent a couple of efforts just wide. Boruc was almost the sinner for Celtic on 78 minutes when he missed a Foran cross but Stephen McManus was on hand to clear the header from substitute Darren Smith.
The Motherwell sub was not to be denied though as he scored a deserved equaliser in stoppage time. Paul Telfer played the ball straight to McDonald who headed to the byline before picking out Darren Smith at the front post and he bundled the ball over the line.