Niall McGinn exploited slack play to double Aberdeen's lead in the 53rd minute and Vyner fired home the second goal of his career on the hour mark.

Aberdeen's first win in four matches, which moved them a point off third-placed Motherwell in the Ladbrokes Premiership, was a triumph in adversity.

With Lewis Ferguson suspended, Funso Ojo out long term and both Craig Bryson and Stephen Gleeson on the bench but not fully fit following injury, Aberdeen were seriously short in central midfield.

McInnes had admitted that Dean Campbell was the only natural midfielder available but started with the teenager on the bench following his part in Scotland Under-19s' midweek victory over their German counterparts.

Leigh and Vyner lined up in the middle with Jon Gallagher ahead of them and McGinn and James Wilson out wide in a 4-2-3-1 formation.

Lewis had already foiled Scott before the fifth-minute penalty, which the goalkeeper conceded when he tried to deal with Shay Logan's short pass-back. Christopher Long nipped in front of Lewis and went down with referee Euan Anderson immediately pointing to the spot despite protests from the Dons man.

Lewis produced his second penalty save of the season when he threw up his left hand to divert the ball over after Scott had shot to the keeper's right.

Aberdeen came into the game and Wilson had a long-range strike saved before Motherwell defender Peter Hartley blocked an effort with his head and went off for treatment.

Barry Maguire temporarily dropped into the back four but was fooled by Leigh's through ball after the stand-in midfielder dispossessed Long 15 yards inside the Aberdeen half. Cosgrove raced forward and chipped Mark Gillespie from inside the box.

Hartley was unable to continue and Motherwell brought former Yeovil defender Bevis Mugabi on for his debut.

The Dons sat back to good effect but sent Cosgrove clear again on the break only for Declan Gallagher to make an excellent recovery tackle.

Motherwell struggled to break down their opponents and when Long got in behind and rounded Lewis, he hit the outside of the post from a tight angle.

Aberdeen's second goal was also the result of Motherwell losing the ball, this time not far from the edge of their own box. McGinn took the ball off Allan Campbell, took a couple of strides forward and lofted a shot into the far corner of the net.

The third came out of the blue as Vyner held off a challenge, turned and fired in off the post from 22 yards.

Motherwell were demoralised and Aberdeen began playing with real confidence. Leigh almost got on the scoresheet when the Dons again turned over possession in the Motherwell half but the former Bury player shot just wide from 18 yards.

Lewis made two decent saves from substitute Devante Cole but the margin of victory might have been greater as Gillespie saved well from Vyner.