Almost four years have passed since Eric O’Sullivan made his, to date, one and only Ireland appearance. In fact, on December 5, it will be four years to the day he came off the bench against Scotland in the Autumn Nations Cup in 2020.

Since then, there have been injuries, dips in form and other props coming into the mix that have meant he has fallen out of the international reckoning, but in the 2024/25 season, O’Sullivan looks like he is recapturing that form that got him noticed by Andy Farrell.

Having played second fiddle to first Rory Sutherland and then Steven Kitshoff, O’Sullivan has re-emerged into the spotlight as Ulster’s first-choice loosehead prop, edging out Andrew Warwick to the starter’s jersey, and the 28-year-old explains just why he’s feeling back to his best.

“It has probably been one of the first pre-seasons for a long time that I have been fit and available for. I have had a couple of shoulder ops in previous years, so I missed pre-seasons,” says the Dubliner.

“I think actually getting a block of training was good for me and, hopefully, that keeps going. I think as a prop, you’re not dying on the pitch, you’re not gasping for air, you are actually able to look up and see what is happening as opposed to just trying to survive.

“Having a block where you can actually work on your fitness, get fit and do four or five weeks’ running and then straight back in.

“I definitely think a full pre-season is good for everybody, you can work on your craft, you can get better at your skills, but it’s just about getting fit.”

The Ireland conversation can wait, though. With Andrew Porter very much ensconced in the green No.1 jersey, soon-to-be most-capped Irish player Cian Healy firmly in as his understudy and even provincial team-mate Tom O’Toole trying his hand at loosehead against Fiji, O’Sullivan knows that he has his work cut out to catch Farrell’s eye again.

“I’m just worried about trying to make the No.1 jersey my own here. If I’m playing well here, hopefully that will happen for me, but I think just play well here first,” he adds.

Part of being able to complete a full pre-season has been O’Sullivan adjusting to the new modern prop dynamic, which has seen scrummaging become less important, with in-goal touchdowns now a goal-line drop-out and scrum free-kicks now not able to be reset.

While Springboks star Ox Nche has proven that stereotypical larger props still have their place in the game, for the most part, modern-day props have become fitter and more dynamic in the loose, and O’Sullivan has taken note of that.

“There is definitely less scrums in the game, but I think, since I have been involved, fitness has always been a key part of it,” adds the front-rower.

“Even when you could pick scrum of those options, even if you weren’t fit, you were just trying to survive in all those scrums as well.

“I think the fitter you can be, you are able to scrum better because you are not tired in every scrum.

“One thing is maybe weight. You might get away with being a bit lighter if there were less scrums, but then you look at a team like South Africa – against them, you don’t want to be light. It’s trying to balance being fit and being heavy.”

Where O’Sullivan is trying to strike a balance between modern and traditional propping, Ulster are trying to strike a balance between moving on for this second block of the season and trying to take the hurt of how they finished the first into Friday’s clash with Leinster.

While three wins from their first five games – their two losses in South Africa nothing to be ashamed about – represented a strong start to their first full campaign under Richie Murphy, the nature of their second-half collapse against Cardiff in their final game before the international break stung.

“We have spoken about that a lot, it was a tough game for us and something that we definitely need to learn from,” grimaces O’Sullivan of a tie that Ulster led 19-0 at half-time but went on to lose 21-19 at the Arms Park.

“We have had a long time to sit and think about it and a couple of tough training weeks, so, looking forward to bouncing back from it.”

No better side to bounce back against than Leinster, the perennial bar-setters and inter-provincial rivals to boot, making for a potentially potent encounter at Ravenhill.

“I think there is always a bit of extra spice when Leinster come to town. They are obviously a very good side, and we know what to expect,” explains O’Sullivan.

“It doesn’t matter if their internationals are away, they will still have a stacked team, still quality individuals that are well-drilled, and I think their League position shows that.

“Obviously, it is bigger because you are playing one of the top teams but, being from Dublin, I don’t think that adds anything for me personally, I love it up here, and here is home for me at the minute. I’m very proud to be representing Ulster.”