American Walter Dix said Olympic and world champion Usain Bolt could "definitely be beaten" at the world championships in South Korea after easing to victory in the 200 meters on the second day of the London Diamond League meeting on Saturday.

Dix was among a number of United States athletes to record impressive wins on a cool day at Crystal Palace, with fellow sprinter Carmelita Jeter and one-lap queen Sanya Richards-Ross also laying down the gauntlet to their rivals ahead of the worlds in Daegu which start on August 27.

Olympic double bronze medalist Dix, the top American male hope for sprint medals in the absence of the injured Tyson Gay, clocked 20.16 seconds into a minus headwind and was pleased by his performance. "All I do is win, that's why you can never count me out. I need a couple of medals at the world championships and people will start to look out for me," said Dix, the US champion at 100 and 200.

The 25-year-old Dix finished ahead of Jamaica's Warren Weir, who clocked a personal best of 20.43.

Bolt may not have been at the meeting, which he also missed last year because of British tax rules on promotional earnings, but he will be the man to beat in Daegu, a task Dix thought was far from impossible when asked about it after his victory.

Another sprinter to watch at the worlds will be Jeter, who has been in consistent form all season and aged 31, will be a contender for a first global title after bronzes in 2007 and 2009.

The second fastest woman of all-time over 100 - only the late Florence Griffith-Joyner has gone quicker - powered down the straight to win in 10.93, ahead of Trinidad & Tobago's Kelly-Ann Baptiste (10.97) and Olympic and world champion Shelley-Ann Fraser Pryce (11.10).

Richards-Ross appears to be hitting peak form at the right time as she heads to Korea to defend her world 400 crown. The 26-year-old, who missed most of last season through injury, lowered her season's best by nearly a second in clocking 49.66. Britain's Olympic and former world champion Christine Ohuruogu trailed in last.