Mbonambi: the Springboks 'Iron' man
The remark made by a rugby coach when he was a junior player is even odder given the 32-year-old Springbok hooker's nickname is 'Iron', like his grandfather who was a body builder, his father Mpinda said in August.
Mbonambi would not be the most physically imposing hooker, he is 5 feet 9 inches (1.77 metres) and weighs less than 16 stone (98 kilogrammes), but he makes up for it with his combativity and his leadership on the pitch.
This combativity is borne out by his motto: "When people tell me I can't do something it makes me try even harder."
The coach who called him out for being too small was neither the first nor the last to eat humble pie due to Mbonambi's determination to prove them wrong.
Outstanding in the 2019 World Cup winning campaign, he has been even better in this edition, man of the match in the 29-28 quarter-final defeat of hosts France.
In a sign of the huge respect he is held in, he is also the man handed the captain's armband when Siya Kolisi goes off.
The significance of his role is underlined by the fact Mbonambi is the only specialist hooker left in the squad after Malcolm Marx, the regular starter, suffered a tournament-ending knee injury before the Romania pool match.
"He is a very important piece of our puzzle, he is definitely very important to us," said defence coach Daan Human.
"He is definitely one of our leaders in the group as well."
Mbonambi -- married to Anastacia with whom he has a daughter Esa who he says with a broad grin is a "right handful" -- has been taught to fight from an early age.
Born in the Free State town of Bethlehem, his policeman father and mother Nombulelo, a nurse, were loving but strict. Mbonambi says he and his siblings "were taught to work hard for what we want".
'Pyjama parties'
He found what he wanted when he went to a predominantly white semi-private school and that was rugby which he also took home with him.
"When I got home I and the only other boy who went to a school that had rugby would play with friends," he recounted.
"We would play with a makeshift rugby ball with newspapers stuffed into a sock and made into an oval shape.
"We would play on open ground or in the middle of the street all day till it got dark.
"That is how my first love for rugby started.
"I think rugby saved me from the worst side of life and showed me a better side."
Mbonambi is perhaps being a bit disingenuous about coming home every day and playing rugby with his friends if his mother's testimony about his school days is anything to go by.
"He never had many friends here in the neighbourhood," she told SABC just after the Springboks had lifted the Webb Ellis trophy in 2019.
"His friends were mostly white from school so he would disappear off with them for pool and pyjama parties.
"He would come back very tired, too tired to even do his homework so all he wanted to do was sleep!" she added laughing.
His mother, who admitted she was nervous about her son taking up rugby as a professional nurse she had seen neck injuries degenerate into paralysis, said Mbonambi never suffered abuse at the hands of the white pupils.
"I can tell you now there was no racial discrimination shown to him from his fellow white school pupils," she said in 2019.
"He never once came back to say he had been bullied, discriminated against or rejected by any of them.
"Colour means nothing to Bongi."