The 28-year-old, who has featured in nine RaboDirect PRO12 fixtures this season, put in a fine display despite filling it at such short notice in what was a convincing 28-6 victory at the Aviva Stadium.
And Tuohy insists it was his memories of tough fixtures in the recent past that helped him quash any nerves and produce an eye-catching performance.
"I just thought to myself, 'Look, I prepped well this week', because you have to prepare well just in case you have to come on in the first five minutes off the bench," said Tuohy.
"So I knew my stuff, that was in the bank. It was just a case of getting my head around being on from the start. I had a good few hours to get my head around it and get into it.
"I said to myself, 'I've played in big Heineken Cup games [for Ulster], I've played against the All Blacks', so I wanted to try to take as much experience from those things as I could.
"It's about backing yourself. I'm getting a bit older. I've worked hard for this and I'm glad that I've got it."
Follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up to our newsletter for regular updates on the RaboDirect PRO12
63x46.png){kind=logo}