The hosts dominated possession in the first half but struggled to break down a resolute Annan defence. Sherwin Seedorf was tricky and enthusiastic down the left but Well missed the creative influence of David Turnbull.

Seedorf's instincts to cut inside allowed Jake Carroll space on the overlap and he found Liam Grimshaw but his tame effort was easily collected by Lyle Avci.

The hosts doubled their advantage on the stroke of half-time through Liam Polworth. The quiet Jamie Semple threaded a perfectly-weighted pass through to Long, who had his shot saved by Avci but the ball fell perfectly for Polworth to slot home.

The second half started without incident until the 58th minute when Grimshaw released Seedorf after a rampaging run but the Dutch winger lacked composure and was thwarted by Avci.

Motherwell have recorded four consecutive clean sheets in Group E and Donnelly has been impressive at both ends of the pitch.

He grabbed his fourth goal in three games when he arrowed an unstoppable right-footed effort into the top corner on 90 minutes.

Substitute James Scott added further gloss to the scoreline when he fired home a fourth in injury time.