Jones will make his first start of the season following his involvement in the Lions tour, while Matthew Rees will play his first game of the season at hooker.

Caldwell is back after an ankle injury along with fellow Ireland international Stephen Ferris, who was a late withdrawal last week.

Scarlets captain Mark Jones and flanker Simon Easterby are both rested, but Wales prop Rhys Thomas returns after missing two games due to a knee injury.

Stephen Jones was rested for last weekend's Welsh Magners League derby to recover from a slight ankle injury but coach Nigel Davies has passed him fit to face Ulster.

Davies said: "Stephen will play for us on Friday which will give him an opportunity to roll into the European game.

"He's massive for us - he has that level of experience and mental toughness on the field that we need for this game. He brings a real composure and understanding to the team and does boss games particularly well.

"It's not only what he does on the field, it is what he contributes off the field as well and he is hugely respected by all the guys."