Ireland coach Eddie O'Sullivan will be happy to see Rory Best back on the Ulster teamsheet after the hooker made a quicker than unexpected return from injury ahead of Sunday's Heineken European Cup meeting with Gloucester.

Best has been sidelined since injuring his ankle in the St Stephens's Day defeat to Leinster, but was named in the Six Nations training squad earlier in the week and will be crucial to O'Sullivan's plans should Jerry Flannery be found guilty of stamping on Julien Bonnaire next week.

"It is great to have Rory back and a good chance for him to stake his claim for his place in the 6 Nations," said caretaker coach Steve Williams today.

Williams has made wholesale changes to his backline with International Mark Bartholomeusz returning at fullback at the expense of Bryn Cunningham, who drops out of the 22.

Tommy Bowe and Mark McCrea will start on the wings with Paul Steinmetz returning to centre beside Andrew Trimble.

Scumhalf Isaac Boss, who was omitted from the Ireland squad this week, will start alongside outhalf Paddy Wallace.

Bryan Young was also overlooked by O'Sullivan but starts at Kingholm beside Best and Declan Fitzpatrick. Tom Court and Nigel Brady are named on the bench.

In the secondrow Australian Justin Harrison is selected to partner Ryan Caldwell at the expense of Italian international Carlo Del Fava. There is no change in the backrow from the Bourgoin game with Neil McMillan providing cover on the bench.

Gloucester welcome back try machine Lesley Vainikolo after his father's death. The wing did not feature in the last two games against Bath or the Ospreys but has scored nine tries in nine appearances so far this season.

"I have been fortunate to have received a great deal of support but I am really happy to be back, be around the boys again and thinking about rugby," Vainikolo said today.

"It's great I have an opportunity this weekend and I want to go out and repay the faith people have in me. There is a job to do on Sunday and we must make sure we achieve it."

Despite defeat to Ospreys last weekend Gloucester know a win will see them safely through to the quarter-finals. A win could lift Ulster off the foot of the table if Ospreys beat Bourgoin. If that is the case, it will be the Welsh side who qualify from pool two.

Ulster: M Bartholomeusz; T Bowe, A Trimble, P Steinmetz, M McCrea; P Wallace, I Boss; B Young, R Best(c), D Fitzpatrick, J Harrison, R Caldwell, M McCullough, N Best, G Webb

Replacements: N Brady, T Court, C Del Fava, N McMillan, K Campbell, N O'Connor, S Mallon

Gloucester: Iain Balshaw; James Simpson-Daniel, Mike Tindall, Anthony Allen, Lesley Vainikolo, Chris Paterson, Rory Lawson, Nick Wood, Olivier Azam, Carlos Nieto, Peter Buxton, Marco Bortolami (c), Alasdair Strokosch, Akapusi Qera, Gareth Delve.

Replacements: Andy Titterrell, Christian Califano, Will James, Luke Narraway, Gareth Cooper, Ryan Lamb, Willie Walker.