Residents fighting the expansion of the Wimbledon tennis complex are hopeful the project will be rejected after planners concluded it does not outweigh the "substantial harm to and loss of" protected open land.
The plans, which includes 38 new courts in Wimbledon Park, one of which will be an 8,000-seat showcourt, scored a major victory last month when members of Merton Council voted to back them.
But a smaller section of the site in south-west London lies within Wandsworth and its planning officers have recommended councillors reject it ahead of a meeting to discuss the project next week.
They said the development would result in the loss of open space and there were no "very special circumstances" that outweigh the harm that would cause.
"By reason of the substantial harm to and loss of visual and spatial openness identified to Metropolitan Open Land, the development would constitute inappropriate development," Wandsworth planning officers said. "It is not considered that there are any 'very special circumstances' that clearly outweigh this harm."
The All England Club wants to build on a site in Wimbledon Park, which used to be owned by a golf club and is classed as Metropolitan Open Land, given a form of protection that treats such spaces in London in a similar way to the green belt.
Wrangling over the plans began about two years ago, when the club first submitted proposals for the site of the world-famous tennis tournament.
Resident Susan Cusack, spokeswoman for Save Wimbledon Park, which is challenging the plans, told The National the group was “happy” with the planners' recommendation but “hasn’t won anything yet”.
She said she was hoping the council would recommend rejection because the group had had “quite a lot of positive support” from Fleur Anderson, the MP for Putney in the area.
“It is a London-wide issue and a countrywide issue," said Ms Cusack. "Cities will be looking at this planning application because if this is allowed to go through it means that Metropolitan Open Land is up for grabs by developers.
“So this is not a Nimby [not in my back yard] issue. This is much, much wider issue. And it really is about the environment and biodiversity, and putting concrete in the ground.”
The group plans to hand in a 15,000-signature petition opposing the project to Wandsworth Council on Friday, ahead of next week's meeting.
The new showcourt has created the most concern among planning officers, who concluded the project did not include the necessary "very special circumstances" to outweigh the harm to and loss of protected open land.
A representative for the All England Lawn Tennis Club (AELTC) said: "We are surprised that planning officers at the London borough of Wandsworth have recommended refusal of the AELTC Wimbledon Park Project, particularly after the London borough of Merton resolved to approve the application following extensive analysis and debate, both in their officers' report and at the planning committee.
"We regret that Wandsworth's officers have taken a different view but it is for councillors on the planning applications committee to make their own considered decision at the meeting on November 21.
"We firmly believe the AELTC Wimbledon Park Project will deliver substantial social, economic and environmental benefits, including 23 acres [nine hectares] of newly accessible green space, alongside hundreds of jobs and tens of millions of pounds in economic benefits for our neighbours in Wandsworth, Merton and across London."
The project will be referred to the Greater London Authority and its fate could ultimately be decided by the government, irrespective of the decision by Wandsworth Council.