Wayde van Niekerk will forever be reminded of that fateful afternoon in October 2017, when an innocent charity touch rugby match put his career in peril.

South Africa's 27-year-old sprinting stalwart, who had just added the 400m world title to his Olympic triumph in Rio, suffered a major knee injury early in that exhibition game, a setback that saw him only return in earnest in February.

But he's stopped being too hard on himself for riskily participating in undoubtebly a worthy cause.

"I can't blame anyone else for my injury," Van Niekerk told worldathletics.org.

"I'm the one who made the decision to play a rugby game, the one who put myself in that position. I'm a professional athlete and the decision I take is on me but what that (brought was) a bit of guilt and wishing I did not do what I did.

"But it was my reality, it happened and putting blame on it wasn't going to get me to come back stronger."

Van Niekerk instead purposefully got on with his rehabilitation and was even aiming for a defence of his world title at last year's World Championships in Doha.

The nature of his ACL tear though meant he would be frustrated in those efforts, with an untimely bone bruise in the knee proving decisive.

"I would have random hamstring pains, calf pains, but my biggest one was the bone bruise. Those setbacks threw me off and they really affected me massively," said Van Niekerk.

"With an injury like an ACL, there are so many setbacks where you need to take a step back and make sure you're making responsible decisions that won't hurt you or cause any more harm. I had to be very cautious to find the line between pushing my boundaries and not overdoing it."

His persistence paid off when, after clocking 10.10 and 20.31 over 100m and 200m at a small, unofficial track and field meeting, he won Free State's provincial 400m title in 47.42.

Van Niekerk admitted it was a "massive boost".

"There were definitely a bit of nerves, questions. But I decided to put all those aside and see what my body wants to do.

"It showed me I still have that speed and I definitely still have the strength that I had before the injury."

The postponement of the Tokyo Olympics has allowed him to "work on specific areas that need attention" and currently his biggest challenge is staying in touch with his 78-year-old coach, 'Tannie' Ans Botha, a difficult thing to do in times of social distancing.

"I stood outside at her fence (one day) and found out how she's been,"said Van Niekerk.

"Things are a bit difficult for her but it's the safest decision for her to stay home. Tannie is very driven, very motivated to get up every day, so this is a time where I need to step up and make sure she's fine. She doesn't have that opportunity to work with us the way she'd love to so us athletes need to take responsibility."