Wilson will start on the bench, with the backrow lineup comprising Ward, Neil Best on the flanks and Campbell Feather at No. 8.
Given that back-row cover Matt Mustchin is also now out for 6-8 weeks with medial ligament damage, McCall's backrow options were becoming desperately limited. It seems that you only have to look at the backrow these days to get injured.
Ward and Wilson's fitness may well be the shot in the arm that gets Ulster going again, and certainly it will engender greater optimism amongst the fans streaming into Ravenhill tomorrow evening.
The backline is unchanged from last week, and both Ronan McCormack and Nigel Brady retain their starting positions in the front row.
Cardiff are one spot ahead of Ulster in the Celtic League, and are surely suffering from their 49-13 thumping by Munster last week. Nick Walne has replaced Freddie Tuilagi on the wing with Jonny Vaughton switching wings while Craig Quinnell teams up with Deiniol Jones in the second row.
Given that the two other sides in the group are Gloucester and Stade Francais, both sides will be eyeing each other up as their best chance to get a win under the belt and give their seasons a platform from which they can push on.
Replacements: 16 - Paul Shields; 17 - Rod Moore; 18 - Rowan Frost; 19 - Roger Wilson; 20 - Neil Doak; 21 - Paddy Wallace; 22 - Jonny Bell
Cardiff Blues:Craig Morgan; Nick Walne, Rhys Williams, Tom Shanklin, Jonny Vaughton; Lee Thomas, Dean Dewdney; Gethin Jenkins, Gareth Williams, Martin Jones, Craig Quinnell, Deiniol Jones, Nathan Thomas, Kort Schubert, Martyn Williams (captain)
Replacements: Andrew Lewis, Rhys Thomas, Robert Sidoli, Nathan Budgett, Richard Smith, Nick Macleod, Shaun James