Goalkeeper Graeme Smith was not forced into a single save throughout the match as Kilmarnock failed to master the blustery conditions.
Mark McGhee kept faith with his fluent playing style despite the atrocious weather and also with the team that defeated Inverness in their last outing, leaving Stephen Hughes on the bench after recovering from injury.
Such continuity Jim Jefferies can only dream of as his team suffered yet more injuries beforehand and had stalwart Frazer Wright suspended.
In 16 SPL games this season, Jefferies has only been able to name the same defensive unit two games in succession on two occasions.
He was able to give a first start to Moroccan international Mehdi Taouil, who was the only bright spot on a bleak day for Killie fans.
Kilmarnock began with a midfield diamond formation with Taouil at the peak and he caused Well a few problems as he relished the space he could find and orchestrated Killie's best move of the first half by picking the ball up from Danny Invincibile and driving at the Motherwell defence at pace.
He cleverly played in James Fowler, but he scuffed his attempted return ball, setting the tone for Killie's afternoon.
Jefferies had called for his players to start more brightly than in recent weeks and they responded initially but soon fell out of the match.
They made it through to the break level, thanks as much to luck as skill, particularly following some sloppy defending at a corner which allowed the ball to reach Chris Porter at the far post.
His header squirmed out of Alan Combe's gloves but fell the wrong side of the post for the striker.
The decisive goal came within a minute of the restart when O'Donnell's speculative 30-yarder brushed Simon Ford's foot and wrong-footed the helpless keeper before hitting the back of the net.