Ireland’s preparations for today’s Pool A clash against Russia included a training session against local club Kobelco Steelers.
McGrath knows their head coach Dave Dillon from his time working at St Michael’s College.
The 26-year-old said: “He was actually my PE coach in St Michael’s for a while. It was just funny seeing a face like that. He coached myself and James Ryan.
He remembered. He’s a great character and doing really well with Kobe. I was a good student because I liked PE”
The scrum-half’s feelings on the Rugby World Cup so far lend a more mixed view.
In the 27-3 mauling of Scotland, he replaced Conor Murray on the hour and with the game won.
And during the 19-12 humbling to Japan, he was brought on for the injured Rob Kearney whose departure and that of Chris Farrell prompted a massive rejig in the Ireland line-up.
Jordan Larmour was brought on in midfield with Jacob Stockdale moving back to full-back with McGrath lining out on the wing.
So he is chuffed to get a start in his normal position.
He said: “I was absolutely delighted to get the nine jersey this week. I’m really excited. I didn’t play nine last week so I’m excited and looking forward to it.”
His first job this summer was to get a place in the squad.
Which meant seeing off the challenge of both Ulster’s John Cooney and Connacht’s Kieran Marmion because of Schmidt’s intention of taking only two scrum-halves.
That was no mean feat considering he missed all of the Six Nations this year, as he had in 2018 too.
He said: “I get injured just before that but it’s been positive all summer.
“My knee that has been causing me issues has settled down, so I’m really looking forward to getting into it and starting my first World Cup game.
“To get the nod ahead of someone with Kieran’s quality was brilliant. All summer it was a really highly-contested position.
“There is only two of us here at the moment and Joey Carbery is covering nine. I feel very lucky and privileged to be part of this squad.
“I’ve have gone well with Leinster and put my foot forward at times.
“It’s just about getting this opportunity on the big stage and proving that I can play here.”
Few acquitted themselves well against Japan and McGrath said there is an eagerness to make amends.
McGrath said: “It was obviously very disappointing. We had a meeting and were very honest with each other.
“We had a tough 24 hours after it but the leaders in here have spoken about it, it’s a five-day turnaround so we have no choice. It’s best that we look forward rather than back.
“We’ve looked back at things we can do better but we’ve had to move on which, is a good thing.”
“He screams at me to get the ball out quicker. When I make a wrong decision, he lets me know. No, I’m only messing.
“He’s been brilliant. He tries to get perfection with everything and it shows how good he is.
“I really enjoy playing with him. It’s like having a teacher out there.
“He knows what to do at the right times. I just listen to him and hope he’s happy.”
And that advice has, in turn, been passed to Carbery.
The New Zealand-born player left Leinster for Munster last summer because of No 10 game-time being limited because of Sexton’s presence.
That move has served him well but the numbers game has meant that he has been primed to also cover scrum-half which he will do from the bench today.
McGrath said: “Conor and I have sat down and gone through moves.
“It’s just a little bit different from nine and 10. He knows the moves inside out, but it’s just a few different roles and a few tips here and there. I’m sure he will be ready.
“One of the challenges is that there would be a bit more running. He has to get to every single ruck.
“Myself and Conor were laughing at him there last week, he couldn’t believe the amount of running.
“He seems to read the game very well and he knows that from 10. He knows what a 10 wants so it’s just about him providing the ball.”
The humid conditions have proved a challenge at this World Cup but McGrath is upbeat Ireland can adjust.
He said: “It’s defintely something we’re wary of. You don’t often see people lose their footing quickly and the ball was very slippy so there were a lot of knock-ons.
“We have plays where we can kick it a little more and play like it’s a rainy day at times.
“We’re aware of it so hopefully we can adapt.”
©News Group Newspapers Limited in England No. 679215 Registered office: 1 London Bridge Street, London, SE1 9GF. “The Sun”, “Sun”, “Sun Online” are registered trademarks or trade names of News Group Newspapers Limited. This service is provided on News Group Newspapers’ Limited’s Standard Terms and Conditions in accordance with our Privacy & Cookie Policy. To inquire about a licence to reproduce material, visit our Syndication site. View our online Press Pack. For other inquiries Contact Us. To see all content on The Sun, please use the Site Map. The Sun website is regulated by the Independent Press Standards Organisation (IPSO)