CELTIC LEAGUE: Week 20: Friday, April 8Cardiff Blues v Ulster, Arms Park, 7.10pm (live Setanta Sports Ireland/BBC Wales)
Coach McCall had named his starting line-up on Tuesday with the only changes coming up front, but a late hamstring strain to Ireland fly-half David Humphreys sees Paddy Wallace drafted in at half-back, and Adam Larkin earning a bench place.
Ireland prop Simon Best switches to loose-head, while Ronan McCormack drops to the bench.
Gavin Pfister replaces broken jaw victim Neil Best - who is out for the rest of the season - in the back row.
Long-time lock favourite Gary Longwell, meanwhile, will make his 150th appearance for Ulster at Netherdale.
The 35-year-old - who made his senior debut against Cornwall in 1991 - made his 100th Heineken Cup appearance against Wasps four years ago. He also recently joined an exclusive band of players who have made 50 appearances in Europe's premier competition.
As well as Longwell's milestone, Ulster confirmed the departures of scrum-half Neil Doak and Kiwi second row Matt Mustchin earlier this week.
Former international cricketer Doak is to retire from the Ravenhill scene after 15 seasons in white, and resume his position as a High Performance coach for the IRFU.
Kieran Campbell's elevation to first-choice pivot under McCall, has seen Doak's starting chances severely hampered this season.
Mustchin, meanwhile, has penned a two-year deal with Edinburgh Rugby, ending his two-year stay in Belfast.
The 28-year-old is hopeful of bowing out of the province as a winner - as he bids to help third-placed Belfast Harlequins to AIB League glory, in the interim.
An injury-plagued 2005 has seen Mustchin feature in only six Celtic League ties.
Another forward Tim Barker also revealed on Thursday that he is to end his contract with the province. The 23-year-old will spend the next two seasons with Glasgow.
Head-to-head since 2003: Cardiff 2, Ulster 3League form: Cardiff: WLWLL; Ulster: LLWLWTop scorers: Cardiff: Lee Thomas 90 points / Dean Dewdney 4 tries; Ulster: David Humphreys 81 / Tommy Bowe 7
Cardiff: Nick Macleod; Chris Czekaj, Rhys Williams, Tom Shanklin, Craig Morgan; Nick Robinson, Ryan Powell; John Yapp, Gareth Williams, Gethin Jenkins/Ben Evans, Craig Quinnell, Robert Sidoli, Robin Sowden-Taylor, Kort Schubert, Martyn Williams (Capt).
Replacements: Ben Evans/Nathan Llewellyn, Rhys Thomas, Nathan Budgett, Nathan Thomas, Maama Molitika, Dean Dewdney, Tristan Davies/Jonny Vaughton.
(15) Bryn Cunningham(14) Tommy Bowe
(16) Nigel Brady(17) Ronan McCormack(18) Campbell Feather(19) Tim Barker(20) Neil Doak(21) Adam Larkin(22) Scott Young
Referee: David Changleng (Scotland)