RIO DE JANEIRO — Despite racing down the stretch of the 400-meter final with a substantial lead Sunday night, South Africa’s Wayde van Niekerk still thought someone was going to catch him. He was wrong about that, very wrong. Niekerk had such a large lead, not only did no one come close to catching him, not even world-record holder Michael Johnson could have done so while running in his prime.

Er, make that former world record holder Michael Johnson. Van Niekerk broke Johnson’s 17-year-old record by .15 seconds, winning Sunday’s race with a time of 43.03. The gold-medal time was nearly half a second faster than van Niekerk’s previous best, which he set when he won the 2015 world championships last summer in Beijing.

And he did so despite running in Lane 8, becoming the first Olympian to win gold in that lane in the 400.

“I felt very alone at the end. I was thinking, ‘What’s going on? What’s going on?'” said van Niekerk, 24. “It kind of gave me motivation to keep on pushing and keep on pushing to the finish line. I dove for the finish line. And right after that, I went down on my knees and thanked God and my family and everyone for tonight.”

Van Niekerk’s time was .73 seconds faster than silver medalist Kirami James of Grenada. American LaShawn Merritt, who won gold at the 2008 Olympics, took bronze with a time of 43.85.

“I didn’t handle the last part of the race as well as I would like but I got a medal,” Merritt said. “I’ll take it and get a day rest and get ready for the 200.”

Merritt said that he knew the race would be fast but he didn’t realize it was going to be world-record fast. But the man can run fast, and at many distances. In addition to a sub-44 second 400, he has run a sub-20 second 200 and sub-10 second 100.

As amazing as Van Niekerk’s run was Sunday, here’s something just as incredible. His coach is his 74-year-old great grandmother Ans Botha. Seriously, a great grandmother.

“She has played a huge role in who I am today and kept me very disciplined and very focused on the role and who I need to be,” he told reporters. “I’m very grateful my coach has pushed me to the limit.”

Van Niekerk also trained for a while in Jamaica, where he met Usain Bolt, who won his seventh gold medal just minutes after the South African won his first.

“I’m really proud of him,” Bolt said. “When he came to Jamaica, I said to him, ‘You’re the only person who can break the 400 meter world record.’ Because he’s very fast and he keeps on going. I wasn’t really surprised he broke it tonight because he’s really good and he looked in good shape.”

Van Niekerk said that Bolt inspired him, along with Michael Johnson. “These are amazing guys. I learned from them,” he said. “Even the guys I ran against today — James, LaShawn Merritt — these are guys that inspired me.”

Asked what his race strategy was, van Niekerk said he didn’t know and laughed. Then he said that he was just determined to run the best he possibly could. He said he was able to do so partly because he had God — and the people of South Africa — on his side.

“I believed in myself as an athlete and my abilities, but tonight God showed how important he’s been in my life,” he said. “And I’m really grateful for the blessing he’s continued to give me in my life. I can say tonight that God is great.”

Van Niekerk was pretty great as well.