Both Inverness and Motherwell went into this game boasting three and nine-game unbeaten runs in the SPL respectively and it was the visitors who threatened first as Jim O'Brien fizzed a shot from close range into the side of Ryan Esson's goal on six minutes.
Caley Thistle prodded and probed in search of the opener, but it was the Steelmen who created the more notable opportunities, Stephen Hughes forcing Esson into a 19th-minute save.
A minute later, it was his opposite number, Graeme Smith, who had to look lively with a smart stop to prevent Eric Odhiambo from turning in Richie Foran's low cross.
Neither goalkeeper had been seriously tested, but a blunder by Esson on 26 minutes handed Motherwell the game's opening goal.
Stephen Craigan's long free-kick tempted Esson to surge out of his box only for the Caley Thistle number one to have the ball pinched from in front of him by John Sutton, who did well to adjust his body and hook a 20-yard effort into the unguarded net.
The hosts' response was almost immediate, however, as three minutes later Ross Tokely's improvisation from an Ian Black free-kick so nearly produced a goal, but his effort dipped a yard over the crossbar.
Inverness had struggled to hit the heights of their previous four games under the guidance of manager Terry Butcher, yet they are nothing if not persistent and their efforts paid off on 39 minutes.
Black's corner was headed towards goal by Tokely and, although Odhiambo had his initial shot blocked, Grant Munro was on hand to smash home the loose ball.
Caley Thistle started the second half on the front foot, but it was Motherwell who regained their lead after 53 minutes.
Munro's mistake allowed on-loan Celtic striker Cillian Sheridan a sight of goal and from the angle of the box he lashed home a fine effort that found the net via the inside of the post.
Caley Thistle huffed and puffed in search of an equaliser and should have levelled on 75 minutes, but Dougie Imrie's centre was headed well over from six yards by substitute Adam Rooney.
The hosts did appear to have decent claims for a penalty in stoppage time, but referee Mike McCurry wasn't interested as Inverness slipped to their first loss with Butcher in charge.