Christine Ohuruogu is confident she will have the last laugh at the World Athletics Championships as she attempts to defend her 400metres title.

The Londoner has been written off in some quarters for the Berlin event after a poor season so far was further hampered by a hamstring injury which forced her to pull out of races on the grand prix circuit.

Main rival Sanya Richards has been running two seconds quicker than Ohuruogu this season in those races but the Londoner is the one who holds the World, Olympic and Commonwealth titles and has never lost a major championship final.

"I have never really gone into a championship super fast," said Ohuruogu. "I find it very comical people like to say that I'm not in form.

"In the week before the 2007 championships in Japan I was running 53 seconds.

"I am fit, healthy and happy and when I have those three I am good to go. My coach always says 400m is not about who is fastest or strongest but who has the strongest will to hang in till the end.

"It's been a difficult journey, as it always is. Every year has been different and you have to face it and deal with whatever is in front of you."

Ohuruogu famously returned from a 12-month suspension for missing three drugs tests shortly before winning the world title in Osaka in 2007.

And after adding the Olympic title in Beijing last year, the 25-year-old believes such adversity has worked in her favour.

"It has been a learning process. The last three years have made me a stronger person," she added. "Being able to accept the challenges and get on with it has given me an advantage.

"These things you have to go through make you see track and field in a bigger perspective."

Speaking about the hamstring injury, Ohuruogu added: "It was not really serious but the timing was not great. I have come here to do a job and if I was not fit enough or healthy enough I would not be here."

Ohuruogu, who will run in the heats on Saturday, was cagey when asked about her rivalry with Richards, who looked set to win the Olympic title in Beijing but paid for going too fast in the first half of the final.

"Everyone has their own regime and preparation," she added.

"I don't want to waste any more energy with deciding how to break other people down. I would rather focus on building myself up."

Meanwhile, Paula Radcliffe will run in the New York City half-marathon on Sunday - her first race in 10 months - before deciding whether to compete in the World Championships marathon a week later.

The 35-year-old Briton had surgery on a bunion on her right foot in March.