Steve Coogan has joked that his co-star Éanna Hardwicke was on "Roy Keane mode" while they filmed Saipan, the highly-anticipated film about the infamous sporting quarrel between the Irish footballer and Mick McCarthy.
Appearing on Friday night's Late Late Show, Hardwicke said it was "terrifying" to premiere the drama at the Cork International Film Festival on Thursday evening.
Speaking about the reaction to the film in his hometown, he said: "I sat in the audience and thought this is a mental idea, we're going to premiere this film in Cork in front of Corkonians, and within five minutes they'll be able to turn around and say 'Nah'.
"Thankfully it went down a treat, and it was very special. That was my local theatre, I did plays there as a kid, I've been going there my whole life, so it was a very special homecoming."
Hardwicke stars as Keane, and Coogan plays McCarthy in the drama which explores their highly-publicised fallout during Ireland's 2002 World Cup preparations.
Keane was sent home following the public quarrel with McCarthy, and the incident divided public opinion in Ireland about who was to blame.
Coogan gave his two cents on the saga: "It's an interesting story, Roy and Mick were at each other's throats.
"When I read the script I thought it was a little bit too pro-Roy, it didn't quite give Mick enough credibility - as a second-generation Irishman as he was, and I am. I think in the end what we did in the film, it's fairly evenhanded. I'd say it's probably 51(%) Roy, 49(%) me."
Hardwicke revealed that he was a long-time fan of his Saipan co-star.
"First day of college, Trinity, I was going to The Lear and we got to sign up for all the societies," he said. "I signed up for the Philosophical Society and who was giving the talk but Mr Steve Coogan. I am and was a huge Steve Coogan fan. I went to see him talk, he was brilliant, and about an hour later I saw Steve at the back, so I doorstepped him, and you were very lovely."
Years later, when Hardwicke and Coogan ended up on the same call-sheet for Saipan, the Cork actor said he tried to play it cool with his famous co-star.
"Because I was such a fan going in, I did that classic thing, which I would advise no one to do - I'm not going to tell him I'm a fan. If anything I'm going to go in and be ruthlessly professional," Hardwicke joked.
"I probably went too far the other way and I was probably very standoffish for the first week. Looking across at everyone having a great time and going 'That looks like fun'. After the first week things relaxed a little and then we had a ball, we had a great, great time."
"I do remember thinking you were in a very Roy Keane mode, should I say," Coogan interjected. "I thought, will I be friendly with him or will that spoil the magic of them being at loggerheads? I went over and said, 'Are we alright?'
"And I think we warmed up a bit. I certainly felt there was a bit of, let's not get too friendly early on, because we need a preserve this conflict."
Coogan went on to praise Hardwicke as a "startling young Irish actor who has an incredible career ahead of him".
"On the first day of set he became Roy - I was shocked by how good he was," Coogan continued. "I thought, I'm going to have to bring my A-game, because he was so focused. It's like having a good sparring partner, he raised my game."
"It's lovely to hear you say that," Hardwicke said. "When you get into a scene with a brilliant, brilliant actor like Steve is, it makes your life 20 times easier.
"Your performance is in their hands, it's the greatest gift when you arrive on set and think, 'This is going to be fun actually'. It's easy to forget yourself, and lose yourself in that way."
Saipan is set to be released in Irish cinemas on 1 January, 2026.
The Late Late Show, Friday nights at 9.35pm on RTÉ One and RTÉ Player.
