CELTIC LEAGUE: Week 22: Friday, April 15Ulster v Llanelli Scarlets, Ravenhill, 7.05pm (live Setanta Sports Ireland / BBC Wales)
McCall has named an unchanged line-up from last week's 22-8 loss to Cardiff, with Rory Best's inclusion ahead of Nigel Brady on the replacements bench, their only alteration.
Llanelli's pride will have been massively dented by last weekend's surprise 57-30 home loss to Glasgow, and McCall is predicting a backlash from the Welsh.
"We would expect a reaction from Llanelli and they are playing to secure a home draw in the Celtic Cup but we will be the more motivated side," insisted McCall."We made a lot of mistakes against Cardiff and lost ball at the break down, but we have been constantly working and we are capable of turning it around."
Having lost three of their last five league ties, Ulster will be doubly determined to succeed in what could prove to be skipper Andy Ward's final game before he takes up his coaching post at Belfast Harlequins.
"Andy is one of Ulster's greatest players, this is his last Celtic League game but we hope he has another two are three games left to play," said McCall of the 117-cap veteran.
"We want to give him and the fans a performance."
Head-to-head since 2004: Ulster 1, Scarlets 2League form: Ulster: LWLWL; Scarlets: WWWLLTop scorers: Ulster: David Humphreys 81 points / Tommy Bowe 8 tries; Scarlets: Gareth Bowen 149 / Aisea Havili, Matthew Watkins 6 each
(15) Bryn Cunningham(14) Tommy Bowe(13) Kevin Maggs(12) Paul Steinmetz(11) Scott Young(10) Paddy Wallace
(16) Rory Best(17) Ronan McCormack(18) Rowan Frost(19) Campbell Feather(20) Neil Doak(21) Adam Larkin(22) Andrew Maxwell
Scarlets: Barry Davies; Garan Evans, Tal Selley, Steve Thomas, Lee Byrne; Gareth Bowen, Mike Phillips; Phil John, Matthew Rees, John Davies, Vernon Cooper, Adam Jones, Simon Easterby (Capt), Andy Powell, Jonathan Mills.
Replacements: Ricky Davies, Aled Gravelle, Chris Wyatt, Ian Boobyer, Dwayne Peel, Aled Thomas, Ifan Evans.
Referee: Andrew Ireland (Scotland)