Having established a 62-point lead after the first four events, the 32-year-old from London in Ontario - who has earned a reputation for being the event's Mr Reliable - pulled up in the 400 metres, grabbing his left hamstring before subsiding to the Hayward Field track.

He laid on the ground for a number of minutes before being helped up.

"I'm not sure what happened," Warner said to CBC.

"I felt my hamstring pull a couple of times.

"I was in lane one so it felt like it was pretty tight.

"I was trying to stay in my lane.

"I felt like something went wrong and I couldn't continue."

It was an unhappy turn of fate for Warner, who won the world indoor title in March and secured a seventh victory at the traditional Hypo-Meeting in Gotzis.

But he had to withdraw from the Canadian Championships before these World Athletics Championships as he nursed a chronically sore knee.

"It's pretty disappointing," Warner added.

"This competition has been the screensaver on my computer the last couple of years.

"I had a chance to compete in front of my son and my girlfriend.

"It's tough."