While he says off the pitch he is “a very easygoing, fun guy”, opposing players whether in Tests or in the English Premiership — he plays for the Sale Sharks — see a very different side to him on the pitch.
However, he admits standing at only 5 feet 7 inches (1.70 metres) he had to develop a feisty side.
“It definitely has something to do with it,” he said.
“Especially growing up, always being told: I’m too small, I’ll never make it.
“I’m a good player but not big enough.
“From a young age, I wanted to show that I can make the tackles that the big guys do, that I can do all the physical stuff.
“I wanted to prove to them that I can do what they say I can’t.”
De Klerk — capped 30 times since making his Test debut in the 2-1 home series win over Ireland in 2016 — says he has to always be snapping at the heels of his opponents to let them know he is around.
“The other thing is: if I’m not going to go 100 per cent against these guys, I’m going to come off second best,” he said.
“So I need to give everything to stay in the fight.”
– ‘A healthy squad’ –
He says he was just the same when he played cricket and was a wicketkeeper.
“There, I was very, very annoying!” he said.
De Klerk’s success at Sale has also acted as a magnet for several fellow South Africans to come to the club, in some cases acting as a recruiting sergeant.
“I helped with a few guys,” he said.
“In the beginning, when we were a bit short in a few positions, Dimes (Sale’s director of rugby Steve Diamond) would ask me: ‘Do I know of anybody who will fit into the group?’
“I am thinking of guys like Rohan (Janse van Rensburg) and Rob (du Preez), who came over for the short term, fitted in really well but ended up staying.”
De Klerk — who hopes to add Premiership success this season with Sale in third position — says although the South Africans enjoy each other’s company they do not hang out together exclusively.
“The biggest thing for us as South Africans is we can’t speak our native tongue the whole time,” he said.
“If we are alone, say, walking from the gym to the changing room, we’ll speak Afrikaans, but if someone joins us, we’ll switch back to English.
“It’s not a problem for us, but if we do speak Afrikaans too much, the boys let us know we are in England now.
“It shows a healthy squad when guys can give each other some stick.”