The champ has been struggling with a knee injury ever since October 2017 when he tore his anterior cruciate ligament in a celebrity rugby match.
And after returning to action earlier this year, the 27-year-old has warned the world that they have not yet seen the best of him.
His current 400m record stands at 43.03s and asked if sub-43 is now his target, Van Niekerk tells worldathletics: “It’s got to be.
“I’m someone that’s stuck on going sub-43 and with that I want to improve my 100m and 200m times.
“I believe I’ve got the abilities to be competitive internationally in all three events.”
Of the injury that has sidelined him over the past few seasons, Van Niekerk says: “I can’t blame anyone else for my injury.
“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.”
Of what got him through the tough times, he adds: “Knowing myself and spending time with my mentors, it made it easier to snap out of the dark places when the negatives were creeping up on me. It helped me seek a positive or a peace within this chaos...”