Two key groups opposed to the building of Brighton and Hove Albion's new stadium at Falmer have said they will not issue any further legal challenges.
The original application for the stadium was made in 2001
Falmer Parish Council and the South Downs Society said they could not fight on as it was clear the government was determined the stadium should go ahead.
Secretary of State for Communities and Local Government Hazel Blears gave the project planning approval last month.
The other main opponent, Lewes District Council, has already admitted defeat.
The planning application for the 22,000-seater stadium on land north of Village Way, in Falmer, was submitted to Brighton and Hove City Council in 2001.
The proposals went through two public inquiries and a High Court challenge over the next six years.
"We have fought long and hard to protect this irreplaceable corner of our beautiful South Downs," said South Downs Society chairman John Songhurst.
"It is clear the government is determined to ride roughshod over its own policies on protecting the countryside to allow this huge concrete carbuncle to be built on virgin downland."
The parish council said the stadium was a tragedy for Falmer.
But it said the decision not to challenge it had been made after taking legal advice and because it did not have an inexhaustible supply of money.
The South Downs Society said it would keep a close eye on the stadium site.
"The developers have been instructed to fulfil certain conditions and the society will ensure these are met," said director Jacquetta Fewster.
The official deadline for objections to the stadium approval is 3 September.