After losses to Leicester and Toulon, Ulster will be determined to bounce back when they host the Scarlets at Ravenhill on Saturday.
Ulater are at the bottom of the table with just one point gathered from those two matches while the Scarlets are in second spot – alongside Leicester – after losing their opener to Toulon before beating the Tigers at home.
Ulster have been boosted by the return of Ruan Pienaar and Dan Tuohy, who have recovered from injury and have been named in the Ulster starting XV.
It will be Pienaar’s first appearance of the season, while Tuohy returns having suffered a broken arm against Cardiff in September.
In total, Ulster head coach, Neil Doak, has made four changes to the side that lost narrowly to Munster in Limerick, with Ireland internationals Tommy Bowe and Robbie Diack also returning to the side.
The front row remains unchanged with Callum Black and Wiehahn Herbst starting either side of captain Rory Best.
Tuohy returns alongside Franco van der Merwe in the second-row, Roger Wilson, who will make his 40th European appearance for Ulster, is selected at openside. Nick Williams continues at Number 8 and Diack comes in on the blindside.
In the backs, Pienaar and Humphreys start together for the first time since Ulster’s European quarter-final win over Munster in 2012, while Stuart Olding moves from fullback to inside-centre alongside Darren Cave.
Craig Gilroy starts on the left wing, with Bowe on the right, while Louis Ludik begins the game at full back.
Forwards Rob Herring, Andy Warwick, Declan Fitzpatrick, Alan O’Connor and Clive Ross, join backs Paul Marshall, Stuart McCloskey and Michael Allen on the bench.
Meanwhile, the Scarlets have welcomed the return of their international stalwarts for this crucial clash.
Scarlets head coach Wayne Pivac has made four changes, one positional, to the starting XV that outmuscled Leicester Tigers at Parc y Scarlets in the second round.
All Black centre Regan King makes a return to outside centre after a lengthy spell on the sidelines having made his return to action Connacht last weekend whilst Michael Tagicakibau returns to the wing.
In the pack Jake Ball returns to the second row having been a late casualty ahead of the last round and man of the moment James Davies replaces John Barclay on the openside flank.
“Great to have the Welsh boys back, especially after that win against South Africa,” said Pivac.
“They’ve come back full of confidence.
“Ulster are a strong set piece side with a very good scrum and have one of the best defensive records in the domestic league.
“They’ll be a hard nut to crack away from home, having said that we’re going there sitting in second place. We’ll be going there with a view of putting our best foot forward and trying to get a result.
“They need to win or it’ll be all over for them. There’ll be a big crowd and we’ll be up against it but it’ll certainly a good challenge.
“We need to get our performance back up to where we were against Toulon and Tigers in the opening two rounds.”
Form: These two sides met on the opening day of the Guinness Pro12 season and played out a 32-32 draw at Parc y Scarlets. Ulster are unbeaten on home soil this season, while the Scarlets are still searching for a first away win of the campaign, although they did manage a draw at Edinburgh back in September.
Ulster: 15 Louis Ludik, 14 Tommy Bowe, 13 Darren Cave, 12 Stuart Olding, 11 Craig Gilroy, 10 Ian Humphreys, 9 Ruan Pienaar, 8 Nick Williams, 7 Roger Wilson, 6 Robbie Diack, 5 Franco van der Merwe, 4 Dan Tuohy, 3 Wiehahn Herbst, 2 Rory Best (c), 1 Callum Black.
Replacements: 16 Rob Herring, 17 Andy Warwick, 18 Declan Fitzpatrick, 19 Alan O’Connor, 20 Clive Ross, 21 Paul Marshall, 22 Stuart McCloskey, 23 Michael Allen.
Scarlets: 15 Liam Williams, 14 Harry Robinson, 13 Regan King, 12 Scott Williams (c), 11 Michael Tagicakibau, 10 Rhys Priestland, 9 Aled Davies, 8 Rory Pitman 7 James Davies, 6 Aaron Shingler, 5 Johan Snyman, 4 Jake Ball, 3 Samson Lee, 2 Emyr Phillips, 1 Rob Evans.
Replacements: 16 Kirby Myhill, 17 Phil John, 18 Rhodri Jones, 19 George Earle, 20 Lewis Rawlins, 21Rhodri Williams, 22 Steven Shingler, 23 Gareth Owen
Date:Saturday, 7 December
Venue: Kingspan Stadium, Belfast
Kick-off: 19:45 GMT
Referee: Luke Pearce (England)