Aberdeen won their second league game of the season thanks to James Wilson's goal in the 6th minute. Making his home debut, the Man Utd striker latched onto a Niall McGinn through ball and produced a great touch and finish.
Four changes were made to the side that drew with St Johnstone last time out. Cosgrove, Devlin and Ball all returned to the starting XI along with Manchester United loanee James Wilson who made his home debut for The Dons.
Coming into the match Stephen Robinson's Motherwell sat two points adrift of The Dons. Last season the fixture proved unpredictable, with both sides exchanging victories across the course of the season as the sides met five times, including in both of the cup competitions.
But from the first kick, Aberdeen looked in the mood and back at Pittodrie for the first time in three weeks the players looked comfortable in the opening stages.
James Wilson got The Dons and his home debut off to a dream start. The number nine latched onto a clever reverse pass by Niall McGinn, took a touch to get the ball under control then finished smartly across Trevor Carson to give the home side the lead.
It was a great team goal and no surprise McGinn was involved again - the Northern Irishman has now been involved in ten goals in his last 9 games against Motherwell (four goals and six assists).
The Steelmen nearly had an equaliser out of nothing just after the twenty-minute mark. Carl McHugh swung his right foot at an effort from twenty-five yards, the ball never looked to trouble Lewis but it swerved at the last minute and struck the angle between bar and post.
The effort had Motherwell rejuvenated and they were beginning to find their feet in the game after a quick start from the home side. They had a penalty appeal waved away after Elliot Frear got in behind The Dons defence - Andy Considine had to make a last-ditch tackle which the referee deemed fair and signalled for a corner which eventually came to nothing.
At the other end, Shay Logan did well to win a free kick in a dangerous position for The Dons on the right-hand side of the penalty area. Both GMS and McGinn stood over the ball but it was the latter who hit it - McGinn's effort had Carson scrambling across his goal but the ball had too much swerve on it and curled out past the right-hand post.
Cosgrove went close just before the break. A good counter attack following a Motherwell corner, saw the striker get on the end of McGinn's cross but he couldn't direct his header on target.
Tom Aldred became the first player to go in to referee Nick Walsh's book for a late challenge on Cosgrove. The big striker had the afterburners on and was travelling at speed before the Motherwell defender brought him down and received a deserved yellow card as The Dons looked to break. That was the last action of a first half which was fairly comfortable for the home side but with only a one-goal advantage the visitors were still in the game.
Out came the teams for the second half and Aberdeen looked to replicate their explosive first half start in the second. GMS looked lively down the wing and forced an excellent challenge from Tait to win an early corner. Devlin got on the end of the set-piece but he couldn't divert his header goalbound and Motherwell cleared.
The Dons did well to withstand some early second-half pressure from the visitors. After enjoying a relatively quiet afternoon, Joe Lewis was called into action on 51 minutes. Elliot Frear turned Considine and had a pop from 25 yards. The ball bounced just before Joe but the keeper got his body behind it and made an awkward save look relatively simple.
GMS continued to look dangerous down the right-hand side, elegantly gliding past defenders at will and producing some lovely touches to open up the Motherwell defence. On the other side Niall McGinn went close with an attempt from the edge of the area but once again his curling effort failed to work the goalkeeper.
Just after the hour mark, McInnes made his first change of the afternoon - goalscorer James Wilson making way for Bruce Anderson. The Manchester United loanee received a well-deserved standing ovation from 14,000 Dons fans inside Pittodrie.
GMS nearly doubted the advantage in the most unusual circumstance. The winger did well to cut inside from the right-hand side and get an effort on goal. He didn't quite catch it cleanly but Carson made a hash of it and the ball went straight through him. Fortunately for the Motherwell keep the ball trickled agonisingly wide of the far post and spared the goalkeeper's blushes.
As the clock ticked into the final quarter the game became scrappy with neither side able get control of possession and dictate the game.
With fifteen minutes left to go Anderson had a great chance to put the game beyond all doubt. Shay Logan did brilliantly to break forward from defence. The right-back timed his pass perfectly to release the young striker, one-on-one with the goalkeeper Anderson lost his composure and fired his shot over the bar.
With 10 minutes left to play McGinn made way for Dean Cambell who came on to make his first appearance of the season.
Motherwell offered a late charge to get an equaliser. A bouncing ball in the penalty area had Dons fans hearts in mouth, the danger wasn't cleared and Elliot Frear went down in the box. All eyes looked to the ref but thankfully for The Dons he opted to book Frear for diving rather than pointing to the spot.
The Dons looked to kill the game in the final few minutes, bringing on Max Lowe for Cosgrove. With two minutes to play Dom Ball took one for the team and became the first Aberdeen player to go into the book for a professional foul on the halfway line.
In the final few moments Joe Lewis pulled off a magnificent fingertip save to deny Cadden and deny Motherwell a point. Lewis was equal to Cadden's effort from the edge of the box, sticking out a strong left hand to tip the ball around the post. From the resulting corner, McKenna bravely headed out and away and won a free kick for troubles.
That was the final scare for the home side with the remainder of injury time being played deep inside Motherwell territory and Aberdeen ran out deserved 1-0 winners.