Michael Higdon's hat trick helped 3 win over Hibernian at Fir Park Stadium on Wednesday to place Rangers.
Isaiah Osbourne tallied the lone goal for either side in the first half when he beat Motherwell goalkeeper Darren Randolph from six yards.
But the match opened up after the break and Motherwell was back on level terms in the 47th minute when Higdon scored from the penalty spot after goalkeeper Graham Stack fouled Henrik Ojamaa inside the area.
Omar Daley set up Motherwell's second goal when he picked out Jamie Murphy inside the box for a goal from six yards, only for Matthew Doherty to answer back a few minutes later and level the match.
Higdon's second goal came after a pass from Murphy in the 70th minute and he completed his hat trick from the penalty spot five minutes later.
Ivan Sproule pulled a goal back five minutes from time but it wasn't enough to prevent Hibs from dropping its fourth game in the last five.
Motherwell moves to within three points of second-place Rangers with its fourth victory in five matches.
Celtic 2, Dunfermline 0
Charlie Mulgrew scored on a great strike from 30 yards midway through the first half to put the hosts ahead, and the Hoops continued to pile on the pressure before finding a second goal in the 76th minute.
Gary Hooper's low cross was stabbed home at the back post by James Forrest, clinching Celtic's 16th straight win in SPL play and leaving Dunfermline on the bottom of the league having claimed just two points from its last six games.