Rory Best may not have been his team-mate for more than a year but when the former Ulster and Ireland skipper speaks, Eric O'Sullivan still listens.
Of all the messages sent his way in the 48 hours between Thursday afternoon when Andy Farrell named his team to face Scotland and O'Sullivan coming off the bench for his international debut in the win, it was one from his fellow Banbridge RFC man that resonated.
In a whirlwind of a week, one made all the stranger under the restrictions enforced by Covid-19, the benefit of Best's 124 caps of international experience were not to be sniffed at.
His advice for the debutant - savour it.
"Rory was on to me (Friday) night saying to enjoy the night before and just to do what I've been doing," O'Sullivan recalled.
"When someone with all that experience says to you the night before the game what he misses the most, you have to take that seriously.
"I was extremely proud. It's something I've always wanted to do, from my first time playing rugby I wanted to be a professional rugby player and this is the pinnacle of that. I'm so proud to get the opportunity to get out there and represent my country, my family, everyone that's been on to me during the week. It just means so much to me.
"It would have been great to have family and my girlfriend here. Hopefully there'll be another opportunity in the future in front of a full Aviva and we'll get them there."
The 11th player to make his debut for Ireland this year, it is amusing to think that, even with the likes of Kiwis James Lowe and Jamison Gibson Park in that number, three years ago O'Sullivan was the least likely newcomer out of all of them.
Reflecting on his unusual path after missing out on the Leinster Academy, he admitted had the call from Ulster not come in 2017, he'd likely have had to give up on his dream of pursuing rugby as a career.
"It all started when I got the call to play an 'A' game for Ulster (v Jersey in January '17). That's where my journey started into the professional game. I got a call from Kieran Campbell to ask if I was available and I jumped at the opportunity. They'd said if I went well there might be an opportunity in the Academy.
"Before that call, that was probably the year when if something didn't happen for me I was going to have to start focusing a bit more on my education.
"I was studying in DCU at the time and I would have been going into third year so things would have been getting a bit more serious. I would have had to knuckle down a bit. I was delighted to just get that opportunity.
"It's been a pretty good run since then."
Standing on the sidelines as he waited for Cian Healy, the prop he looked up to most as he was making his way in the game, to trot from the field with 15 minutes to go, O'Sullivan added he felt more nervous when making his way to Carton House for the first time a week earlier.
"I think last week was probably more nerve-wracking," he said. "I got the call on Monday to come into camp. I was absolutely delighted to get the call but there's so much to get your head around.
"The first couple of days I barely spoke to anyone. I was just in my room myself trying to learn calls and plays, lineouts.
"Once I got over that initial shock everyone was great and helped with information. It's been a great experience."
A great autumn for O'Sullivan but a more mixed one for Ireland as a whole.
While the three-try win over Scotland, coming after a slow start, was a strong finish to their six-game slate, results like the defeats to France and England, as well as the lacklustre win over Georgia, had head coach Andy Farrell talking of a team on a journey.
While the highs of 2018 don't seem so long ago, the discourse surrounding the team feels a world away, even after wins like Saturday's.
"Obviously everyone knows the stick that we've come in for," said Farrell. "I know Johnny was saying that about the first 15-20 minutes and I think he's correct that up to the 20-minute mark where it was a bit stop/start, but I thought we started pretty well in the first five or six minutes, we had some proper good intent, but I thought the period just before half time we showed our intent especially with the ball.
"At half-time we had a few things to address defensively. We had been a little bit passive from time to time which gave them good inroads and the Scots are a really good attacking side. I thought we defended really well. We switched off once for the try, obviously.
"But I thought we were aggressive. We controlled them really well in that second half and that was the catalyst for the performance in the second half."
Still, the criticism will be levelled that the side have wilted when it has mattered most this autumn, failure in the games against France and England looming larger than the wins.
"That' s the facts, I can't argue with the facts," added the head coach who will hope to have the likes of Tadhg Furlong, Garry Ringrose, Jordan Larmour and Dan Leavy back for the Six Nations.
"I suppose, everyone is talking about England and France putting in some really good rugby but if England or France beat Wales by 30 points or put 31 points on Scotland everyone would be raving about their improvements as a team.
"Scotland are an extremely good side that's improving massively over the last couple of years.
"I think they play a great brand of rugby, physically they've improved massively so to score 31 points against them at home is very pleasing.
"There was always an eye on preparation for what's going to be around the corner after Christmas regarding the Six Nations.
"It's obvious that competition for places is going to be huge over the next period of time because they've got to play against each other (in festive derbies), they've European games.
"But, at the same time, there will be a lot of reflection on what's happened over the last eight weeks and on what we've started and what we need to do to make sure we don't come back in for the Six Nations against Wales having to start again."