Photo: Hall Sports Ventures

Oakland Mayor Libby Schaaf’s call for the city and Alameda County to negotiate exclusively with the A’s on a possible new ballpark at the Coliseum would knock at least two other potential suitors for the site out of the batter’s box.

One is Elon Musk’s Tesla, which has sent a letter of interest to the city about the 130-acre Coliseum parcel. Exactly what the company would build there is a closely guarded secret.

The other is a proposal that arrived at City Hall just hours after Schaaf suggested talking with the A’s alone. It came from Mark Hall, a real estate investor from Walnut Creek who has won the rights for a United Soccer League expansion franchise.

He’s pitching a plan for a 44-acre mega-sports and recreation center on the Coliseum site that would include a stadium for his team and sports fields. He would use Oracle Arena, which the Warriors are about to vacate, for concerts, pro lacrosse games and foosball competitions. (Yes, foosball, the arcade game when little players on hand-manipulated metal rods kick a ball up and down the table.)

The rest of the property would go to the A’s for their new ballpark.

Hall offered $85 million for his portion of the land — or, if the A’s go elsewhere, he’d match the team’s offer to pay off the city and county’s $136 million in debt on the stadium and Oracle Arena in exchange for the property.

But for his deal to work, Hall tells us, it has to be sewn up by July. “We have hot money in our pocket right now,” he said.

If the City Council and county Board of Supervisors go along with Schaaf’s plan, that money will be cooling off quickly.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or email matierandross@ sfchronicle.com. Twitter: @matierandross