TODD  Blackadder has underlined the "real challenge" that awaits his team in Friday's European Champions Cup clash against the Scarlets.

Bath currently top Pool Five in the race for a quarter-final place, but three-time European champions Toulon are level with them and Scarlets lie third, just one point behind.

It is the tightest of this season's five Champions Cup groups, and Bath know that defeat against a side they beat in west Wales three months ago could destroy their last-eight ambitions.

"It is a real challenge," Bath rugby director Blackadder said, ahead of the Recreation Ground encounter.

"We did a lot of homework and analysis on them before the first game, and I can clearly see why they are a quality side.

"They are a team that will come firing. They are still in this competition with a lot to play for, so it's a big game for both teams.

"They are a quality team, and in no way would we underestimate just what damage they can do with the ball in hand."

Bath are boosted by the return of international flanker Sam Underhill, who has not played due to concussion symptoms since England's victory over Australia in November, while wing Matt Banahan also features after recovering from a foot injury.

Elliott Stooke will make his 50th appearance for Bath in the clash.

Stooke starts in the second row alongside the returning Luke Charteris,  while Banahan - who will join Gloucester at the end of the  season, it was revealed this week - comes in on the right wing in a back three that includes Aled Brew and Anthony Watson.

Ben Tapuai and Jonathan Joseph continue in the centres, with Rhys Priestland and Chris Cook at fly-half and scrum-half respectively.

Beno Obano, Tom Dunn and Henry Thomas make up the front row, while Matt Garvey captains the side at blindside flanker, with Underhill and Zach Mercer completing the back row trio.

Leigh Halfpenny has dropped out of Scarlets side after initially being named in the team, as does wing Johnny McNicholl.

Rhys Patchell goes to full-back, Dan Jones to fly-half, Paul Asquith to wing and Hadleigh Parkes is in at centre

Scarlets head coach Wayne Pivac said: "We are really looking forward to the occasion. It's a must-win game for both sides. We both know that.

"It's like a knockout game in itself. Competitive people like these sorts of situations, so we are looking forward to it.

"This week has been about trying to get our attacking game going again. We just have to look back to when we played them (Bath) last time. They were more disciplined and more clinical than we were, and played the conditions better than we did."

Bath: 15. Anthony Watson, 14. Matt Banahan, 13. Jonathan Joseph, 12. Ben Tapuai, 11. Aled Brew, 10. Rhys Priestland, 9. Chris Cook, 1. Beno Obano, 2. Tom Dunn, 3. Henry Thomas, 4. Elliott Stooke, 5. Luke Charteris, 6. Matt Garvey (captain), 7. Sam Underhill, 8. Zach Merce

Replacements: 16. Michael van Vuuren, 17. Lucas Noguera, 18. Max Lahiff, 19. James Phillips, 20. Paul Grant, 21. Kahn Fotuali’i,22. Freddie  Burns, 23. James Wilson.