Dame Tanni Grey-Thompson says Britain may have to accept slipping down the Paralympic medal table at the 2008 Games, which are one year away.
Britain was second to next year's hosts China in 2004, but Grey-Thompson says other countries have been catching up.
"In the past, fewer countries competed at the Paralympics - and it would be difficult for GB to stay at the top of the medal table forever.
"There's a more realistic place for us to be, which is still in the top five."
606: DEBATE
Grey-Thompson, Britain's most successful Paralympian who retired this year, said Team GB's past acheivements should not be taken for granted.
"People expect the team to do well, (and) that is a tough challenge to live up to, especially when you look at the numbers of disabled people in Britain compared to countries like China or the US."
Britain took second place behind China in 2004 with 35 golds - though Canada, USA and Australia were very close behind - and the latter two had more medals in total than Team GB. 2004 Paralympic medal table2000 Paralympic medal table
But British Paralympic Association chief executive Phil Lane is hopeful that GB can retain their second-place standing, though admits they will have to "fight for every medal".
"We're hoping we can keep our position and win the same sort of medals as we did in Athens. If we could remain in second place in the medal table, we would be delighted.
"We have invested in training camps in Macau and Hong Kong to give athletes a chance of dealing with the cultural differences they will face and also things like jet lag and and a change in climate.
"In addition, sports like swimming, cycling and equestrian have done well on the world stage over the past few months.
"It's still too early to set a medal target but in time we will sit down and see what is realistic and let the world know where our ambitions lie."
Indeed Grey-Thompson still believes her successors can make a big impact in 2008 if they raise their game.
"I think Beijing will be a challenge for British athletes but it is going to be an exciting one to see how strong they are and whether they are at the best level they can be."
China - who are sending a huge team of 350-400 participants to the Paralympics - will again be the team to beat but Grey-Thompson urged her successors to rise to the challenge.
CHINA'S DISABILITY CHALLENGE
"We should not accept that because China will have a big team they will win everything," she told BBC Sport.
"They will win a lot but it is a chance for other countries to see how good their Paralympic programmes are."
And she said the fact that China are now so dominant showed how far the Paralympic movement had advanced disability sport.
"I think there is a lot of intrigue surrounding Chinese athletes and we are all waiting to see what they are going to produce and it is almost the fear of the unknown," she said.
"You know that most countries will not be suddenly able to produce 30 wheelchair racers to take on the world but it is quite possible that China can.
"However, we might be working ourselves up into nothing."
BBC Sport will be broadcasting extensive coverage of the Paralympics, which start on 6 September 2008.
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