A sentimental Justin Gatlin hailed Usain Bolt as an "amazing showman" whose career would certainly not be defined by him pulling up with cramp in the world 4x100m relay, the Jamaican's final competitive race.

There was high drama in Saturday's relay as anchor man Bolt received the baton in third place behind eventual gold medallists Britain and runners-up America.

Less than 50 metres down the track, Bolt suddenly pulled up, clutching his left leg, tumbling to the track with what was later diagnosed as a hamstring cramp.

"This is farewell time, I am sentimental about it already now," said Gatlin, who stormed to 100m gold in London, US teammate Christian Coleman taking silver to relegate Bolt to a disappointing bronze in his individual send-off.

"In the warm-up area we give ourselves respect and greet each other," Gatlin said of Bolt, who bows out of competition with a startling haul of eight Olympic gold medals and 14 world medals, nine of which are gold.

Gatlin, who has served two doping bans, put the blame for Bolt's cramp partly at the amount of time the athletes spent on the track before the starter's gun went off.

"There was a cool breeze out there. But the conditions were the same for everybody," said the 35-year-old, who won the 100m at the 2004 Olympics in Athens and the 2005 worlds in Helsinki before serving his second ban between 2006-10 for taking testosterone.

- Chilly conditions unhelpful -

"I think it was the elements. I am sorry he got this injury. He is still the best in the world.

"It was a recipe. I don't want to say this but I understand we need to be ready early but I think we took our clothes off a little too early. It's a little chilly in here so I think that's where the cramp came from. That's what he suffered with. He was running out there cold."

But Gatlin, who was roundly booed at the London Stadium before both the 100m and relay, insisted: "Usain Bolt is a great athlete.

"You can't let this championships define what he's done in the past. He has done amazing things. He's still the man, you know. The was his farewell race and we wish him the best and hope he recovers soon."

Referring to Bolt's mooted future ambassadorial role within athletics' world governing body the IAAF, Gatlin added: "He's coming back in a couple of years. He'll be ready, he has a passion for the sport.

"He loves the fans and they love him. He loves the sport too much to walk away. He's a showman."

Japan snatched a surprise bronze medal, Kenji Fujimitsu moved to comment: "Thank you, Bolt. He was an inspiration for us."

The sport's greatest entertainer was determined that one of the finest careers in sport was not going to end with him in a wheelchair.

So the fastest man of all-time, surrounded by his three worried team mates, Omar McLeod, Julian Forte and Yohan Blake, rose gingerly to his feet and limped the last 30 metres to the line.

Jamaica's Usain Bolt (C) walks with teammates Yohan Blake (L) and Omar Mcleod (R) after pulling up injured in the final of the men's 4x100m relay athletics event at the 2017 IAAF World Championships at the London Stadium in London on August 12, 2017

The official result recorded that the Jamaicans did not finish but Bolt had been absolutely determined to ensure he completed the last race after a matchless career in which he won 19 major championship gold medals.

Typically, Bolt's only thoughts were with the team mates he felt he had let down.

"He kept apologising to us but we told him there was no need to apologise," Forte said. "Injuries are part of the sport."

McLeod added: "It just happened - Usain Bolt's name will always live on."