The 400 metres world record holder Wayde van Niekerk says he wants to become the first athlete to break the 43-second barrier for the one-lap event.

The 28-year-old South African -- who timed 43.03sec in the 2016 Rio Olympics final to set the new mark-- said in a BBC interview with former world record holder Michael Johnson that he is determined to make up for lost time after a couple of years of recovering from a serious knee injury.

Van Niekerk, also a two-time world champion, damaged knee ligaments in October 2017 while playing in a celebrity touch rugby match that preceded a South Africa-New Zealand rugby Test in Cape Town.

His track action this year has also been severely curtailed by the lockdown due to the coronavirus pandemic with the defence of his Olympic crown delayed till next year in Tokyo.

However, he is raring to go and set new benchmarks that will he hopes make him untouchable to his rivals and for those who come after.     

"I have this deep desire to be out of reach," he said.

"And after coming out of a period of somewhat suffering, it makes me more hungry."

The 43-second mark is in his sights.

"It's definitely a priority for me, because why am I still here if I'm not seeking growth?" said van Niekerk.

"Growth should be improving my times within the 42-second range. That's where my mind is at; that's where my heart is at.

"Seeing you (Johnson) set a standard (43.18sec in Seville in 1999) of setting a record of 17 years -- I want to double that.

"That's just the competitor in me and for me to settle for anything less than that would mean I'm doing an injustice to myself and the team working for me."

Van Niekerk -- who has competed in several low-key races on the comeback trail -- admitted he had battled against depression in the weeks after suffering his injury.

"The first two weeks were very difficult and showed signs of me climbing into a dark space," he said.

"So I had to bounce back because I can't be dwelling in this dark space.

"I had to start from scratch; I had to tell myself from the beginning that I need to take responsibility for the decision I've made."

Van Niekerk curses himself still for participating in the rugby match, declaring it "the worst decision to make".

"I knew how to play rugby but I hadn't touched a ball for eight years," he said. 

"My body was conditioned for running straight -- not zig-zags.

"That was the last thing I was thinking of but later on you sit back and realise that the decision was obviously silly."