The Scottish champions won on Italian soil for the first time with a 2-1 Europa League victory over Lazio on Thursday and French striker Odsonne Edouard helped them take care of domestic duties with a 19th-minute opener at Parkhead.
Motherwell defender Richard Tait scored an own goal in the 54th minute to leave the home side ahead of their Old Firm rivals, who won at Livingston by the same scoreline, by a one-goal margin.
Celtic and Rangers both have 31 points after 12 matches. Both teams have conceded seven goals but Celtic have scored 36 compared with Rangers' tally of 35.
Edouard scored the opener after early Celtic pressure.
Olivier Ntcham, Edouard and Mohamed Elyounoussi all fired shots over the bar before Motherwell goalkeeper Mark Gillespie had to beat away a more accurate effort from Jonny Hayes.