NEWPORT Gwent Dragons are confident that James Thomas will boost their lock options for their European Rugby Challenge Cup semi-final in Edinburgh.

The 24-year-old was forced off in the 41st minute of their 25-21 quarter-final win against Cardiff Blues at Rodney Parade last Saturday after being caught in the head by Josh Navidi's forearm when tackling the number eight.

He was helped from the field but was able to join in the post-match celebrations and will undergo concussion tests ahead of Sunday's Guinness Pro12 fixture with champions Leinster at Rodney Parade (kick-off 4.15pm).

Thomas has been a mainstay of the side at blindside flanker since the autumn but is set to be a welcome option at lock, a position he played in the Challenge Cup victory at Stade Francais.

The Dragons will be without Rynard Landman because of suspension at Murrayfield, the final game of the South African's six-week ban, while Andrew Coombs is likely to be absent with the knee injury suffered at a lineout after 11 minutes against the Blues.

The Wales international was forced off and the Dragons expect to learn the extent of the damage in the coming days.

Cory Hill was superb in the second row against his former region last weekend while other options in Edinburgh are Matthew Screech and Ian Gough. Joe Davies, who impressed for Wales Under-20s in the Six Nations, is not registered in the European squad.

Director of rugby Lyn Jones is faced with a dilemma for Sunday's clash with playoff hopefuls Leinster, who have a Champions Cup semi-final at Toulon looming.

The Dragons are on a three-match winning run and will be keen to keep their momentum, as well as staying above the Blues in the table, but they are also wary of a five-day turnaround to their Murrayfield date.

Centre Pat Leach had hoped to have a reunion with his old Rydal Penrhos School midfield partner Andrew Fenby in the last four but is content to settle for a clash with Edinburgh, who triumphed 23-18 at London Irish on Sunday.

"We are used to playing Edinburgh so know what to expect," he said. "It will be a hard game but we have done pretty well away from home this season.

"It's the biggest game since I have been at the Dragons and hopefully we can use the experience of the quarter-final, forget about the occasion and go out there and play some rugby."