With a semi-final berth at stake, the Motherwell manager's energies will be wholly focused on the advancement of his Fir Park side who enjoy home advantage. "A semi-final place is a tremendous incentive for both sides," said McLeish, who has a full squad to choose from apart from his long- term injury victims, Mitchell Van der Gaag and Miodrag Krivokapic.
"Both sides know a lot about each other, so I doubt if there will be any surprises. With the forwards playing well for us and for them it could come down to how either side defends."
McLeish's charges claimed three victories over his old club in his first season at Motherwell last year and Aberdeen are likely to be unchanged from the side that drew 1-1 with Hibernian on Saturday, with the goalscorer, Duncan Shearer, sidelined.
"We are looking to challenge for honours in every trophy we enter as quickly as possible," said McLeish's counterpart, Roy Aitken. "A place in the semi-final would help in that and if we play to our potential we can go through."
Hearts, regular semi-finalists in recent years, bid for another under the management of Jim Jefferies at First Division Dundee. Allan Johnston is doubtful for the Edinburgh club with a leg injury but Gary Mackay could return from the start after appearing as a substitute in Saturday's 2- 0 defeat at Partick Thistle.
"That result was a kick up the backside for us," Jefferies said. "We must do better at Dens Park and we were disappointed to create so few chances against Thistle. But this is a great opportunity to get into a semi-final at this stage of the season."
Jim Duffy, whose Dundee knocked out Premier opponents Kilmarnock in the last round, will look to the Scotland Under-21 internationals, Neil McCann and Jim Hamilton, to try and help his side claim a place in the semi-finals. Roddy Manley is injured and there are also doubts over Dusan Vrto and Morten Wieghorst.
In the other tie, Airdrie, of the First Division, play host to Murdo MacLeod's Partick Thistle at Broadwood. Thistle are unbeaten in five games this season since MacLeod quit Dumbarton to succeed John Lambie at Firhill. The striker Rod McDonald is fully recovered from illness and joins the squad which beat Hearts at the weekend, although Tommy Turner is still out.
Alex MacDonald's Airdrie have a formidable reputation for upsetting the odds in cup competitions, however. Last season the Diamonds reached the Coca-Cola Cup semi-final before losing on penalties to Raith and then they went one better by making the Tennents Scottish Cup final only to be beaten by Celtic.Reuse content