- 7 updates
Mo Farah's rival Andy Vernon was 'not surprised' the 32-year-old did not show up at Birmingham Grand Prix on Sunday.
Speaking after the 5000-metre race in which he finished ninth, Vernon said: "I'm pretty sure his mind won't be in the right place for racing and being an athlete I know how important that sort of thing is.
"Also... he's Mo Farah, he's expected to win."
Vernon and Farah have enjoyed a difficult relationship following a social media spat last year.
Olympic champion Mo Farah has pulled out of today's 1500m race at the Diamond League event in Birmingham saying he is "emotionally and physically drained".
"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," Farah said in a statement.
"I want to run well in the IAAF World Athletics Championships in Beijing and have decided it is better for me to go back to the US, seek answers to my questions and get back into training."
"I apologise to the people who bought tickets to come and watch me race and ask for your understanding at this time."
Mo Farah has said doping allegations concerning his coach Alberto Salazar is "ruining my reputation" - but he has no plans to end their relationship.
The double Olympic gold medallist told a press conference he has not seen "any clear evidence" that Salazar had been involved in doping.
"I'm a clean athlete, against drugs and anyone who isn't should be banned for life.
"I want to know the answers and the easiest thing to do would be to jump.
"But if you can't show me proof (Salazar), I'm out. I will be talking to people because it's my reputation", he added.
"The headline is 'Mo coach' and it's not fair on my family, kids. I want the memories, the 75,000 people cheering for me at the Olympics. They should know."
Latest ITV News reports
Ed Warner says if he was a close friend of Mo Farah's he would advise the Olympic champion to suspend his relationship with Alberto Salazar
Farah will not be ending his relationship with Alberto Salazar as he has not seen 'clear evidence' to back up doping allegations