Moone Boy creator Chris O'Dowd may be best known for his funnyman persona, but Deirdre O'Kane has revealed it's not all laughs with him on the set.
The actress - who stars alongside the Roscommon man in the light-hearted comedy - said Chris was serious when it comes to filming.
"Chris can be great fun to work with, but he is also quite demanding," she said.
"He's very driven. People think it's a laugh-a-minute on set, but when you're shooting a series you're under massive time pressure."
While he might be a tough boss, Deirdre said the actor-turned-director's attitude was one of the reasons behind Moone Boy's phenomenal success.
"I think Chris is gifted, massively brilliant," Deirdre (45) said.
"He has a very strong work ethic and demands a lot from himself as well as others.
"That's what made it a very good show."
Deirdre, who recently won an Ifta for her role in Irish film Noble, also opened up about growing older.
While she feels more confident in herself now she's in her 40s, she admitted she worries about losing her looks.
"It's a double-edged sword," she told the Galway Advertiser.
"You do feel liberated in yourself, and you know yourself a bit more, but your looks are fading, which is definitely hard.
"Unless you make a decision in your head that it isn't going to be that important ... but until you reach that point, you fight against it.
"I wouldn't want to be younger, but I'd like to hold on to my looks a while longer - sure, I'll keep throwing money at it," she added.