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."
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
UK Athletics has 'absolutely no concerns' over the conduct and coaching methods of Alberto Salazar in relation to Mo Farah