Maro Itoje's head has been in Moussa's hands for more than a decade.
From behind the barber's chair, Moussa has seen Itoje mature from a much-hyped teenager to a three-time 30-year-old British and Irish Lion.
Now captain for the first time, one of Itoje's final appointments before departing for Australia is to have his mane trimmed.
"It has been a while," says Itoje of his and Moussa's relationship.
"It is going to be a challenge on tour.
"You always have to have some trust - a bit of a leap of faith - when you walk into a new barber's chair. Especially in Australia, where I don't think they are too used to Afro-Caribbean hair!"
Faith, and contingency plans, will be a theme for Itoje over the next five weeks.
When asked about how religion fitted into his tactics, former Labour spin guru Alastair Campbell famously said "we don't do God".
Itoje, who was introduced to Campbell by England team manager Richard Hill as a youngster and remains in touch, definitely does.
At his unveiling as Lions captain in May, he revealed he had missed Bible study to be there.
When he was promoted to England captain in January, his pastor was one of six people he told before the public announcement., external
Asked about the long journey to both posts, Itoje has a simple explanation: "God's timing is always the best time."
"In the last two or three years I have made a conscious decision to double down in that regard," he tells BBC Sport.
"I was probably a lukewarm Christian for a large part of my life. I was probably someone who went to church, but was not really living the principles or values of it that deeply, but I have always been a believer.
"The humility that I have tried to embody throughout my life definitely comes from knowing that everything I have has been a gift, not by my own doing, but by the guy upstairs."
By Itoje's high standards and own admission, that humility wasn't always present on previous Lions tours.
He has described his 22-year-old self, who won over the Lions fans' sea of red in New Zealand in 2017, as "a little bit brash and a bit naive".
This time around, at the very centre of the hype and hoopla, he is determined to keep his calm and routine.