Ulster hooker Tom Stewart says he is primarily treating his participation in Ireland's World Cup build-up and preparations as a learning exercise.

He made his debut as a replacement during the second half of Saturday's 33-17 win over Italy in Dublin.

"I'm just here to learn really. It was a bit of a surprise for me to even be here for the summer," said Stewart.

"I was delighted I got selected.

"For many young boys across Ireland watching rugby the dream is to one day pull on the special green jersey and run out in front of the Aviva.

"The fact I got to do that on Saturday with a lot of good lads and under a bunch of great coaches, it was very special for me and it will always be with me. It will go down as one of my prouder moments playing rugby."

Stewart's inclusion in Andy Farrell's senior international squad follows an outstanding breakthrough season in which he consistently impressed for his province and set the record for the most tries in a United Rugby Championship season with 16.

He was one of seven Ulster players named in the group which will be whittled down to 33 on 28 August for the World Cup itself.

The other three hookers in the extended squad are Stewart's Ulster team-mate Rob Herring, plus Leinster pair Dan Sheehan and Ronan Kelleher.

Stewart credits his involvement in the Emerging Ireland squad which toured South Africa last September as playing an important part in his development.

"It definitely improved my game, I learnt a lot of things about how Ireland want to play their game and a lot of things that suit my game, how I want to play with the tempo and speed they want to play," explained Stewart.

"Getting to know the systems and the coaches, how they like things done and different ideas, how they see the game. It was a big help and went a long way to get me to where I am now.

"Each day I'm just trying to learn off the boys, learn off Dan, learn off Ronan, learn off Rob, see how they go about their day, see how they go about things, and get different perspectives on different areas of the game I'm trying to work on."

Test rugby 'a step up'

The Ulster front-rower has been praised by Farrell for his approach to the game and got in excess of 30 minutes under his belt when introduced off the bench against the Azzurri on Saturday.

"It was definitely a step up, even in terms of preparation before the match and me becoming more professional in my approach to the game - my analysis and recovery and prep, getting my body right for the game," he explained.

"The game itself, it's international rugby, it's a Test match. It was physical, it was tough, scrum wise I thought we scrummed well so that was a big positive for me.

"That was one of the things I was more worried about going into the match and I was happy to come out with it as a positive.

"It's nice to hear the coaches saying good things about you but you have to keep working on things. You can't be complacent, there's always parts of my game I need to work on, and especially from Saturday.

"It was by no means perfect and I've a lot of things to work at and get better at so that will be the main focus from now on."

'A huge amount to offer'

Ireland defence coach Simon Easterby took charge of the Emerging Ireland group which travelled to Bloemfontein to face the Griquas, Pumas and Cheetahs almost 12 months ago.

"He was excellent to work with. A great kid who works really hard, he's diligent and has got a huge amount to offer. He's a real athlete," enthused Easterby.

"He adds a huge amount with his game, his try-scoring figures are pretty high, as are those of Rob Herring and other two hookers. They benefit from a lot of good work that goes on in front of them. All four have the ability to score tries off the back of good mauls.

"Tom has done really well. He's a great prospect and is someone who is really putting his hand up for selection over the last four or five weeks.

"If he gets another opportunity over the next couple of weeks I'm sure he'll do the same."