It took Neil Lennon's only five minutes to take the lead at Parkhead as Kris Commons opened the scoring, giving Motherwell a veritable mountain to climb from the early stages.
Commons doubled his tally for the match six minutes before half-time as he converted a penalty, before a Stephen McManus own-goal in the 69th minute made sure of a home win, despite Anthony Stoke’s late red card.
Aberdeen's hold on second took a knock as they lost to Inverness Caledonian Thistle at Pittodrie.
Danny Williams scored the match’s only goal as Inverness ran out 1-0 winners, moving his side up to fourth and to within seven points of Aberdeen, whom they have a game in hand over.
Dundee United fell further behind Celtic's chasing pack as they were overturned 3-0 away to Ross County.
Filip Kiss gave the hosts a 1-0 lead just before half-time, while Yoann Arquin extended their lead with 21 minutes to go.
Kiss secured all three points in the 74th minute, thus lifting County above Partick Thistle, who dropped points at home to Kilmarnock in a 1-1 draw.
St. Johnstone end the weekend in the top six following their exciting 3-3 draw with Hearts, but it could have been much better as they let a two-goal lead slip , while they also had Steven Anderson and Alan Mannus sent off.
Stevie May scored all three for St Johnstone and they led 3-1 with two minutes left, but Sam Nicholson and Daniel Wilson salvaged a point for Hearts, who themselves had Ryan Stevenson dismissed.
Kallum Higginbotham’s early goal looked to have given Thistle an important win, but just after Aaron Taylor-Sinclair’s 89th-minute red card, Robbie Muirhead equalised to earn Kilmarnock a point.
St. Mirren held off Hibernian’s second-half revival to earn a 3-2 triumph at Easter Road, moving them one place behind their hosts.
The visitors were 3-0 up by the 26th minute thanks to an own-goal from Ben Williams and a strike each from Adam Campbell and Steven Thompson, but Hibs almost snatched a point in the second half.
Jamie Collins netted twice in the final half-hour, but it would not be enough as they fell to their ninth league defeat of the season and move down to seventh.
