Christine Ohuruogu coasted into the semi-finals of the women's 400m in Beijing as the Briton chases a historic third world title.
The 31-year-old, who has struggled for her best form in 2015, was slow out of the traps but she gradually built momentum before winning her heat in a time of 51.01s.
She finished clear of Marie Gayot of France in second, and USA's Natasha Hastings in third.
Ohuruogu, who won gold in Osaka in 2007 and again in Moscow six years later, clinched 400m gold at Beijing's Bird's Nest Stadium in 2008.
