McGrath up for duel with 'world-class' Pienaar
Given the nature of their position, scrum-halves don't quite engage in mano-a-mano battles. They co-exist on the pitch and rarely come into direct contact, but their battle for influence on a game is crucial nonetheless.
Now an established starter at Leinster, Luke McGrath relishes the days when he comes up against one of the market-leaders in his position.
Last week, he edged Conor Murray at the Aviva Stadium and on Saturday Ruan Pienaar comes to the RDS. If Aaron Smith was visiting in two weeks' time, he'd complete the set.
Like Murray, Pienaar is a familiar foe who has added his personal brand of control to the Montpellier backline. Put the former Ulster No 9 behind a large French pack and place Aaron Cruden alongside him and you have quite a combination.
"He is one of the best scrum-halves I've played against," the 24-year-old Ireland international said. "Every single time I play against him, I look forward to the challenge. You are only going to better yourself against this calibre of player.
"You focus on your own game because you don't come into contact too many times.
"What Ruan does so well is every time he is running to the ruck, he is scanning the backfield because he is such a good kicking option.
"You could be on your halfway line defending him, the next thing you know you are five metres from your own line. It is those kinds of things he does so well.
"He is such a world-class player and they have world-class players all over the place."
The ability to see the game in advance and read the play is something McGrath has tried to add to his game having watched Pienaar closely.
"He is just so smart and he has played at ten as well. He's got that natural ability," he said.
"His length of pass is good. He always seems to choose the right option - when to run, when not to run. Even you see him often now, whenever they get a penalty, he takes a quick one.
"He doesn't even let the wingers get set. He just keeps the momentum rolling. It is just those smart little details he does which make him one of the best."
McGrath has always been a leadership figure on school, provincial and international teams underage, but he is adapting to being the junior man in a half-back partnership with a domineering No 10 in Johnny Sexton.
He is learning to assert himself and take some of the decision-making on himself, spotting space and identifying opportunities.
"It was something I learned last year," he said. "Coming up through the Leinster Academy, the running game is what I enjoy. Absolutely.
"I felt that I was doing what I was told rather than trusting my instincts at times. That is something I need to develop more.
"If there is someone, Johnny, or Ross or Joey, screaming at me from the outside, just to have a go for it and. Hopefully, it will be the right option."
Having reached the European semi-final last year, Leinster are determined to achieve in the Champions Cup this year and McGrath says a good start based on limiting errors is key against a talented French side.
The teams played twice last season, Leinster won at home and lost away, but the big-spenders have recruited heavily and are coached by the experienced Vern Cotter who has recruited well.
"They have threats all around the park," he said.
"One way to beat them is not to have many mistakes, if any.
"Their back three is so impressive. The nine and ten run the game.
"They crowd you well and can put you under pressure with any type of game.
"Their maul is very strong as well. It is a massive, massive challenge and if we want to win, we have to be right on our game.
"Pienaar and Cruden will be trying to run their game. If we want to beat them, we are going to have to put pressure on those two."