Usain Bolt has insisted that he has no doubts regarding his form ahead of next month's World Championships in Beijing.

Bolt, the world and Olympic champion, has struggled for fitness in 2015 while rival Justin Gatlin has set the fastest times in both the 100m and 200m.

However, Bolt has backed himself to improve ahead of the event in China, starting with his appearance at the Anniversary Games in London this weekend.

The 28-year-old told reporters: "I never doubt myself. I look forward to competition. Beijing is a month away so I'm not worried about that. I'm trying to take it a step at a time.

"I've got two races this weekend. I've been training really hard. I've been pushing myself, so it's all about execution now."

Bolt has won six Olympic and eight world gold medals during his illustrious career.