Head coach of 110m hurdles world recorder holder Liu Xiang still believes that long-time absentee Ladji Doucoure of France is the biggest rival at the Prefontaine Classic in Eugene, Oregon on Sunday.

"He has not competed in the 110m hurdles since he got injured last year. But Doucoure is young and athletic and will remain Liu's biggest rival in the upcoming competitions," Sun Haiping told Beijing Evening News.

"Even in the 2008 Beijing Games, I till think he will pose the biggest challenge to Liu's defense of his Olympic title."

Liu will face a competitive showdown on Sunday as the world's best runners get together for the first time this season.

As well as world champion Doucoure, making his first appearance after sustaining an injury ten months ago at the European Championships, four-time world champion and veteran hurdler Allen Johnson will lead a strong local line-up including Terrence Trammell, the two-time Olympic runner-up, and Dominique Arnold, whose best time is 12.90 seconds.

Revenge will be on the cards for the challengers, as last year Liu pulled away from Doucoure and Johnson to win the race.

Also the winner in 2005, Liu has his eyes on a hat trick.

"I have adjusted myself very well. The time difference is not a big problem anymore. I will try my best to win again," Liu said.

An in-form Liu, ranked No 1 in the IAAF standings, is coming off from a come-from-behind win at the Reebok Grand Prix in New York last week.

The 23-year-old finished in a time of 12.92 seconds, a season's best, which broke the 13.03-second record in the event set by Allen Johnson in 2005.

Coach Sun said Liu's form is even better than last week.

"Liu feels much better than last week. We have kept on training since the win in New York.

"Now with the world's best all coming together, it is a good chance for Liu to compete with them and better know their form before the world championships in August."

Talking about Liu's top position in the IAAF rankings, Sun said Liu will try to consolidate his advantage.

"The rankings show that Liu is very strong. We want to keep the top position as long as possible."

With the addition of Liu, there are now 12 athletes entered in the meet who were ranked No. 1 in their events last year by Track & Field News magazine.