Shakes-Drayton returns home
Perri Shakes-Drayton has returned home from the World Championships in Moscow for further assessment on her knee injury and so will not race in the 4x400 metres relay, UK Athletics has confirmed.
The 24-year-old sustained the problem during Thursday's 400m hurdles final in which she finished seventh.
The Great Britain team for Friday morning's relay heat is Eilidh Child, Shana Cox, Margaret Adeoye and Christine Ohuruogu.
The news is a blow to the relay squad, who have high hopes of a medal at the Luzhniki Stadium.
Shakes-Drayton is the second fastest British woman over the flat this season, behind individual 400m gold medallist Ohuruogu, with a personal best of 50.50 seconds.
She anchored the British quartet to gold, ahead of the United States in the 2012 World Indoor Championships.
The Londoner's coach Chris Zah has accompanied her on the flight home, where the injury, which is to her left knee, will be fully examined.
She had an ultrasound scan on Thursday night, having said after the race it "felt funny". It certainly hampered her running badly as she hit hurdles and lost her rhythm entirely as she clocked her slowest time of the year.
Tiffany Porter had no problem with the barriers in the 100m hurdles as she looked very smooth in winning her heat in 12.72secs to cruise into Saturday's semi-finals.
The 25-year-old, an outside medal hope, finished ahead of London 2012 silver medallist Dawn Harper-Nelson, who was back in third.
She said: "It was just a matter of working off the cobwebs and just focusing on running a clean race and qualifying.
"The main focus this whole season has been here, the World Championships, so hopefully I can put my races together and come out victorious."
Marilyn Okoro and Laura Muir both went out in the semi-finals of the 800m.
Twenty-year-old Muir was seventh in 2.00.83, while Okoro could only manage 2:02.26 to also finish seventh in the second semi.
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