An "emotionally and physically drained" Mo Farah has withdrawn from Sunday's Diamond League meeting in Birmingham.
The double Olympic champion wants "to go back to the US and seek answers" after a "stressful week" that saw a BBC investigation allege his coach Alberto Salazar had been involved in doping.
There is no suggestion Farah has done anything wrong but he is "angry" at his name being "dragged through the mud".
Salazar strenuously denies the claims made by the BBC's Panorama programme.
Farah spoke publicly about the allegations made in 'Catch me if you can' - broadcast on BBC One on Wednesday - for the first time on Saturday.
And on Sunday Farah, who had been scheduled to run in the 1500m in Birmingham, added: "This week has been very stressful and taken a lot out of me.
"I have not been able to focus properly on today's race and after the events of the last few days I feel emotionally and physically drained.
"I want to run well in the World Championships in Beijing (22-30 August) and have decided it is better for me to go back to the US, seek answers to my questions and get back into training.
|BBC athletics correspondent Steve Cram's verdict:|
|"Mo should have been here today because he could have moved the story on by getting it back to athletics. "Sometimes when you're in a room full of the world's media you can feel very isolated and he would have been more loved here. I can understand it - he's tired, he's emotionally upset - but we wouldn't have minded if he'd got beaten here today and I don't think the supporters would have minded it."I've known Alberto Salazar since 1980. He is a meticulous coach, a meticulous person - he's a detail person and that's what made him the coach people want to go to."He's always looking for ways to push things forward. He was like that as an athlete. Of course, we all expect people like that to push within the rules. This sport is fraught with people who have pushed the boundaries and then occasionally stepped over but we desperately hope - and I have a reasonable amount of confidence in this case - that's not what he's done."|
"I apologise to the people who bought tickets to come and watch me race and ask for your understanding at this time."
On Saturday, Farah, who is the reigning Olympic and world champion over 5,000m and 10,000m, said he had spoken the day before with Salazar about the claims, and that the American had told him "it's just allegations".
However, Farah insisted he wanted further assurances "as soon as possible".
The BBC investigation alleged that Salazar, who became Farah's coach in 2011, violated anti-doping rules and doped United States 10,000m record holder Galen Rupp in 2002 when the athlete was 16 years old.
Rupp, who would later become Farah's training partner, won Olympic 10,000m silver behind the Briton at London 2012. Rupp also denies the doping claims.
Salazar, Rupp and Farah's agent, Ricky Simms, were made aware of the BBC's allegations one month ago. Farah and his agent were together last weekend when he won the 10,000m in Eugene, Oregon.