A supermarket planned for Bristol's Ashton Gate would have a significant impact on local shops, according to a report.
The study, by property consultancy GVA, was commissioned by the city council whose planning committee will consider Sainsbury's application in March.
It said the negative impact of the store, on Bristol City Football Club's ground, would outweigh any benefits.
Sainsbury's said it was still confident of getting planning permission.
In July councillors rejected the original plans for what would have been the South West's biggest supermarket.
Revised plans were submitted in November.
But the report said the impact of the latest plans on retailers in North Street and East Street, in Bedminster, would outweigh any benefits.
It said "the scale of impact on Bedminster is much higher than predicted at the time of the previous application".
It said the predicted increase in convenience turnover at the new store was twice the former level - £9.7m rather than £4.4m.
The report stated: "It is our view that convenience stores in both parts of Bedminster will lose around £4.4m of turnover and comparison retailers will lose £5m of turnover.
"It is our view that the negative impacts of the proposal outweigh any positive benefits which may accrue."
But Bruno Moore, from Sainsbury's, said: "This report looks at retail impact only and does not take into account the positive benefits that our proposals bring in terms of investment, job opportunities, and regeneration.
"The report doesn't conclude that there's a significant impact, it's not sufficient to refuse planning permission."
The sale of the land would help fund Bristol City's proposed move to a new stadium at nearby Ashton Vale.