Trimble will win his fourth cap and first RBS 6 Nations Championship start on Sunday after being preferred to Ulster team-mate Tommy Bowe on the left wing for the Wales clash.

The 21-year-old is a hard-running back who, despite his wiry frame, can break tackles and has the gas to finish off chances - as his tally of three Test tries proves.

Trimble's promotion to the starting line-up after featuring on the bench against Italy and France is well deserved and he is anxious not be overwhelmed by the occasion.

''The more opportunities you get to play for Ireland the more you want to do it again and again,'' he said.

''Every match you grow in confidence and you grow in experience. I would like to think I improve as a player every game.

''I want to keep doing that. I want to keep learning from the players around me. I would not have anticipated having three caps at the beginning of the year.

''That's the way it is and now the goalposts move and I want to achieve more and more.

''It's important not to get overawed by it all. I am playing international rugby and I want to contribute.''

Trimble has been playing most of his rugby at centre for Ulster - he also made his Ireland debut in the number 13 shirt - and concedes he would rather operate in the midfield.

''All I can do is go out and play whatever position I am picked to play in but I think I would rather play in the centre,'' he said.

''I have a bit more experience there and I feel a bit more comfortable there. But whether you have got 13 or 11 on your back, it doesn't really matter.''

Hooker Jerry Flannery has been given the all clear to face Wales in Sunday's clash at Lansdowne Road.

Flannery, Ireland's first choice hooker for the tournament, sustained an ankle strain in training earlier in the week but passed a fitness test on Friday.

Shane Byrne, drafted into the squad as cover, returns to Saracens for their Premiership clash with Bristol.