Dwain Chambers last night withdrew from the 200 metres in Edmonton following an injury to his left hamstring after qualifying for the second round by finishing fourth in his heat.
Chambers, who finished fifth in Sunday's 100m final, was clearly in trouble from the halfway point and crossed the line with a grimace on his face.
He had an icebag strapped to the back off his thigh when he announced he would be taking no further part in the event. He said: "I'll see if I can be ready for the [4x100] relay."
Canada, it seems, just cannot shake off the stigma of Ben Johnson. These world championships were supposed to be about helping rebuild the image of a sport here shattered by the positive drugs tests of Johnson.
That was slowly happening until it was announced yesterday that the Canadian sprinter Venolyn Clarke had tested positive for stanozolol, the same banned anabolic steroid which Johnson had been found guilty of using and which saw him stripped of his Olympic 100 metres gold in Seoul 1988.
Clarke, who like Johnson was born in Jamaica, had failed to qualify from the second round of the 100m on Sunday after finishing fourth in her heat. She now faces a two-year ban from the sport.
Adding to Clarke's embarrassment was that she had been quoted in the local newspaper on Sunday as putting her recent remarkable progress at the age of 34, which including winning the Canadian championships and setting a personal best of 11.29sec, down to a revolutionary new training programme that mixed eastern philosophy and western medication.
The schoolteacher from Ontario competed while still unaware she had failed an out-of-competition drugs test conducted in Calgary last Tuesday. The weekend before, she had finished second in the Francophone Games in Ottawa, where she also won a silver medal in Canada's 4x100m team.
Britain has reassured the International Association of Athletics Federations that it remains committed to staging the 2005 world championships despite doubts surrounding the future of the building of a new stadium at Picketts Lock.
The sports minister Richard Caborn yesterday concluded a short visit to the Edmonton championships by hosting a reception for leading IAAF officials to allay fears that the government wanted to abandon the project, which was a manifesto promise in the run-up to the general election.
Patrick Carter, the businessman heading Jack Straw's review committee into the future of Picketts Lock and Wembley, accompanied Caborn throughout his trip.
Caborn said: "I had a very productive meeting with Lamine Diack, the president of the IAAF. I was very pleased to have had the opportunity to reaffirm the total commitment of the government to the 2005 world championships.
"This is a commitment from the prime minister down, and is not considered negotiable. We will meet all the deadlines set for us by the IAAF.
"The fact that we are here in Edmonton means that our team can learn a lot at first hand about what it takes to organise such a major competition."
Caborn also met the new IOC president Jacques Rogge tin Edmonton to discuss a possible London Olympic bid in 2012.