Saracens' taskmaster coaches might have Billy Vunipola on a tight leash, but the England number eight admitted tough love from older brother Mako keeps him in line.
Wrecking-ball loose forward Billy Vunipola has long since hailed Saracens' regimented coaching team for whipping him into international-calibre condition since his switch from Wasps last summer.
Now the 21-year-old has revealed the threat of a dressing down from older brother Mako has been just as integral to his meteoric rise with club and country.
The Vunipolas will line up together in Saracens' ranks for Saturday's Aviva Premiership semi-final against Harlequins at Allianz Park.
After graduating from Bristol's academy, Billy joined Wasps and Mako headed to Saracens.
The Vunipolas' influential parents could hardly bare to watch their sons trade blows in Premiership battle, but now they are among the same set of troops Billy is happy to fall into Mako and Saracens' regimented plan.
"When we played against each other, I think that was the tipping point," Billy Vunipola told Press Association Sport after scooping the Land Rover Discovery of the Season accolade at the Aviva Premiership awards.
"That year, that changed things. It's made it easier for our family, for them to come to support one team.
"It's great to be in huge occasions and to be able to have those experiences alongside my brother.
"He pushes me hard in training too, if there's ever a time where I might slack off or something, he gives me a clip round the ear!
"So I think I've definitely benefited from being back close to him, and the coaches at Saracens have really helped me improve as well."
Nick Easter will become Harlequins' most-capped star in the professional era in Saturday's last-four league tussle, the former England number eight surpassing Ceri Jones' record of 232 appearances.
Both teams are at full strength, with Saracens resisting the temptation to mix up selection given their Heineken Cup final clash with Toulon in Cardiff just a week later.
Billy Vunipola will pack down in the back-row alongside tackle machine Jacques Burger and gritty Scotland skipper Kelly Brown.
The Australia-born number eight said Saracens must produce their famed defensive zeal to have any chance of progressing to the final.
Acutely aware there are no prizes for topping the regular-season standings, Vunipola said Saracens must hold their nerve as they chase a European and domestic double.
"We finished top of the table with the most points ever in Premiership history in the regular season, but I don't think that counts when it comes to semi-finals," he said.
"It could be a great season for us with the Heineken Cup as well, but could is what it's all about and that's all it is at the moment.
"As a team we've been trying to block that out, it's tough and we know that, but we're just battling to focus on the job ahead this weekend.
"It's my first time coming top of the table so I can't really say whether there should be a trophy for the regular season as well.
"Maybe for the Leicesters and the boys who have been up there a few times they would have wanted that, but being my first time I just want to win the whole thing!
"All I'm thinking about is trying to win this game this weekend."