Three-time world champion Nick Matthew has been accused of being past his peak by one of his biggest rivals for this year's crown.
Matthew, 34, will open his World Squash Championship defence against a qualifier in Qatar on Saturday.
But Egypt's world number one Mohamed Elshorbagy, 23, said: "Even if he plays his best he will not play as well as he used to play when he was at his peak."
Matthew said Elshorbagy must respond to going from "hunter" to "hunted".
World number three Matthew, who won his second successive gold in the Commonwealth Games in Glasgow in August, is scheduled to face Elshorbagy in the semi-finals.
The Egyptian beat Matthew in the final of the Qatar Classic at the same venue last year.
|Recent men's world champions|
|2013||Nick Matthew (Eng)|
|2012||Ramy Ashour (Egy)|
|2011||Nick Matthew (Eng)|
|2010||Nick Matthew (Eng)|
|2009||Amr Shabana (Egy)|
"Mohamed has been the hunter throughout his career so far but now he's become the hunted and it's how you react to that challenge and that position that determines a lot," Matthew said.
"When I got to number one for the first time it was quite tough. I think I dealt with it better second time around and I'm old enough now to be past the stage where I put unnecessary pressure on myself.
"I know if I'm in my best form in Doha next week and do myself justice, then I know I can be challenging in the latter stages and I'm really looking forward to it."
Gregory Gaultier of France, who lost to Matthew in last year's final in Manchester, is the top seed in a 64-man field.
The event, which starts on Friday and runs until Friday 21 November, also features two-time champion Ramy Ashour and four-time champion Amr Shabana.
British former world number one James Willstrop, Matthew's long-standing rival, misses out through injury.
The women's World Championships take place in December at Niagara on the Lake, Canada, with Britain's Laura Massaro the defending champion.