"We have got to play out of our socks and be mentally prepared, if we are going to come away with the win which we really need."
In the pack, the Ulster management have made a number of changes, with Ireland prop Court donning the number 1 jersey, alongside returning hooker Brady.
The versatile Dan Tuohy moves to blindside flanker, while Caldwell comes in to partner Ed O'Donoghue in the province's second row.
Number 8 Chris Henry will once again captain the team, with Fijian flyer Nagusa drafted in as the only change to the backs division.
Meanwhile, the Scarlets have three Wales internationals back in their matchday squad in the shape of centre Jonathan Davies and hookers Ken Owens and Matthew Rees.
Scrum half Martin Roberts has also returned to the Scarlets for the rest of the Six Nations and will start on the replacements bench against Ulster.
New Zealander Regan King will start his third game for the region since returning from a long-term hamstring injury, while young backs Tavis Knoyle and Dan Newtown, along with Llandovery clubman Joe Ajuwa, have been included in a fresh-looking Scarlets back-line.
Newcastle Emlyn's Josh Turnbull gets a start in the back row, with Richie Pugh returning in the number 7 jersey.
SCARLETS: Dan Newton; Joe Ajuwa, Regan King, Jonathan Davies, Andy Fenby; Rhys Priestland, Tavis Knoyle; Iestyn Thomas, Ken Owens, Deacon Manu, Lou Reed, Dominic Day, Josh Turnbull, Richie Pugh, David Lyons (capt).
Replacements: Phil John, Matthew Rees, Rob McCusker, Johnathan Edwards, Martin Roberts, Daniel Evans, Gareth Maule.
ULSTER: Jamie Smith; Timoci Nagusa, Darren Cave, Paddy Wallace, Andrew Trimble; Ian Humphreys, Isaac Boss; Tom Court, Nigel Brady, BJ Botha, Ed O'Donoghue, Ryan Caldwell, Dan Tuohy, David Pollock, Chris Henry (capt).
Replacements: Andi Kyriacou, Bryan Young, Robbie Diack, Willie Faloon, Paul Marshall, Niall O'Connor, Simon Danielli.
Referee: Peter Allan (Scotland)
Assistant Referees: Nigel Owens, Greg Morgan (both Wales)
Television Match Official: Nigel Whitehouse (Wales)
"We have just come back to the team hotel after a lovely walk through the centre of Swansea and now are about to have lunch. The players will rest up during the afternoon, and then we will leave for Llanelli and Parc y Scarlets at 4.45pm.
"With regard to the game we have to be really positive tonight, we have been improving our performances away from home, it is something that we talked about at the beginning of the season, but at this crucial stage of the season we must really make this count.
"We need to be very accurate with everything we do. The Scarlets have an experienced squad, but we have to be clinical with the chances we create and come away with the right result."
Nigel Davies (Scarlets) - "Of course we are under no illusions what a hugely important game this one is, we are not hiding from it. We have just got to win this game.
"We were frustrated with the result at Leinster, not in the manner of our performance which was positive, but that we let a game slip through our hands that we were in control of, and had plenty of opportunities to finish off.
"Ulster have been doing very well, I've been impressed with their performances. They started slowly in the Magners but have really picked up their game recently and they have some good players in key positions - with a couple of good wingers.
"They have been rebuilding for a couple of years and it looks likes they have a good academy and good foundations to build off. They are very ambitious moving forward as their recruitment drive is starting to show."
Top Scorers - 2009/10 Magners League: Scarlets - Points: Rhys Priestland 65; Tries: Jonathan Davies 3; Ulster - Points: Ian Humphreys 95; Tries: Simon Danielli 5
RECENT LEAGUE MEETINGS:
Saturday, March 3, 2007 - Scarlets 17 Ulster 11, Stradey Park
Friday, October 12, 2007 - Scarlets 32 Ulster 8, Stradey Park
Friday, February 29, 2008 - Ulster 20 Scarlets 8, Ravenhill
Friday, September 5, 2008 - Ulster 9 Scarlets 16, Ravenhill
Saturday, May 16, 2009 - Scarlets 43 Ulster 17, Parc y Scarlets
Friday, October 2, 2009 - Ulster 45 Scarlets 24, Ravenhill
- The Scarlets' only victory in their last five matches in the Magners League was a 14-9 triumph at the Newport Gwent Dragons on New Year's Eve
- The Welshmen have lost their last seven clashes with Irish teams in all competitions this season
- Ulster have not lost since their 15-3 reversal to Leinster at the RDS in the Magners League on December 26, and are unbeaten in their last three encounters with Welsh teams
- Ulster's only loss in their last four matches with the Scarlets in all competitions was a 43-17 defeat at Parc y Scarlets in the Magners League on May 16, 2009
- Ulster won 45-24 when the two sides met at Ravenhill in round 5, but have never achieved a league double over the Welsh region in the same season