Dina Asher-Smith's chances of Olympic glory could be hampered by a year's delay to the Games, according to Iwan Thomas.
Reigning 200 metres world champion Asher-Smith was one of Britain's best prospects for gold in Japan this year.
But the 2020 Tokyo Games have been pushed back until July next year because of the coronavirus outbreak and British 400 metres record-holder Thomas believes an extra 12 months' preparation time could count against Asher-Smith.
"For some it'll be a good thing," said Thomas, a member of the British men's team that won 4x400m silver at the 1996 Atlanta Games.
"I felt for Dina Asher-Smith who is mentally and physically at the top of her game.
"She might still improve but being the current world champion you are there to be shot at and people fear her a little bit.
"They would have gone in fearing her but one year on you could say she was on the crest of a wave, what a shame she's been paused.
"But for others it's a godsend to have another winter's training behind them. It's the same for everyone, advantage and disadvantage."
Thomas was set to run the London Marathon for Group B Strep Support on Sunday after his son Teddy suffered from the potentially fatal condition when he was born.
But with the virus delaying the race until October, he is now taking part in the 2.6 charity challenge that is being staged on Sunday instead.
"The London Marathon raised £66.5 million ($82.2 million, 76 million euros) last year and that's money charities rely on," he said.
"This particular charity is so close to my heart, that is what will get me through the marathon when it really starts to hurt.
"I'll be forever in the NHS's (National Health Service's) debt for saving Teddy."