Alex McLeish's side raced into a three-goal lead thanks to a Gregory Vignal brace and a Dado Prso effort, but were forced to withstand a late fightback as Kevin McBride and Martyn Corrigan found the target and Gers midfielder Barry Ferguson was sent off.
Rangers stung the hosts with an early goal for the fourth time this season, when Vignal blasted a right-foot volley high past Gordon Marshall from 15 yards out in only the fourth minute of the match.
Well responded with a couple of weak Scott McDonald efforts which were hit tamely at the keeper from long range.
It took Rangers until the 24th minute to create their second shot at goal, but Nacho Novo's effort was blocked for a corner by Stephen Craigan.
Paul Quinn sent David Clarkson through into the box but the young striker chose to cross and his effort was cleared by Sotirios Kyrgiakos for a corner.
However, Terry Butcher's men were punished for not making the most of their opportunities when Vignal scored his second after 32 minutes, rising to meet a Rae cross with his head before the advancing Marshall.
Once again the home side tried to respond but found Ronald Waterreus in top form when he dived full length to turn a Scott Leitch 25-yarder round the post.
Motherwell made a spirited start to the second half forcing Waterreus into action to collect a number of teasing balls into the box, but once again they were punished at the other end.
Six minutes after the break Prso bulleted a near post free-kick into the net off the far post, to put the game well beyond the home side.
Undeterred the home side plugged away and found a goal after Bob Malcolm handled a Steven Hammell cross in the 71st minute. McBride stepped up to
take the penalty and fired his effort high past Waterreus.
The game burst into life in the 79th minute when Clarkson was late on Fernando Ricksen and Richie Foran followed it up by clattering into Ferguson. The Gers midfielder retaliated to earn his second yellow card of the afternoon.
Within minutes Motherwell narrowed the gap to one when Foran found Corrigan at the edge of the box and the midfielder's shot spun off Malcolm to leave his keeper helpless.
It was game on, but the home side could not find the third goal to level the score.