SAN DIEGO (CBS 8) - One day after the mayor's task force revealed financial plans for a new San Diego Chargers stadium, both the Chargers and the Raiders finalized a complex land transaction for 170 acres in Carson. 

The good news for San Diego Chargers fans who want to keep the team in San Diego is that just because the team is now joint-owners of the land in Carson, in a deal that closed Tuesday morning, it does not mean they have to build a stadium. 

Some Charger fans remain concerned. 

"It'd be a sin to take them somewhere else," said one fan. 

The deal enables the Chargers and Raiders to build a proposed shared NFL stadium on the site, if that is the game plan both teams eventually choose.

The land purchased includes 157 acres of land, which was a former toxic landfill. It sits along the 405-freeway. 

The deal has been transferred from Carson marketplace to a joint powers authority controlled by the City of Carson, and eleven acres have been transferred to a newly created company jointly owned by the Chargers and Raiders. 

"We understand it. We expected that," said Adam Day, Chairman of the Chargers Stadium Advisory Group. 

Adam Day said the Chargers are just keeping their options open. 

On Monday, the Chargers and the Raiders hired Carmen Policy, former president of the San Francisco 49ers, and Cleveland Browns to help spearhead the push for a new stadium in Carson. 

"They're doing exactly what good business people should do, but they've also told us San Diego's their number one choice and so we think that our plan provides them a path forward to stay in San Diego," said Day. 

On Monday, Day's advisory group unveiled a comprehensive new plan to build a new $1.1 billion stadium at the current Qualcomm site in Mission Valley without raising taxes. 

Day said he believes it's a plan to prompt the Chargers to kiss Carson goodbye. 

"I think our plan is very competitive with Carson. It's less risky. There are less unknowns environmentally and politically, as well as financially. Carson is a very risky deal," he said. 

Mayor Faulconer said he is focused on keeping the team in San Diego. He said he is anxious to start negotiations to keep the team in town. 

If the proposed $1.7 billion shared stadium is not built in the land recently purchased by both teams, Carson would retain control of the land and use it as it chooses. 

[READ RELATED: Raiders owner Mark Davis still considers Oakland top option]