SAN FRANCISCO -- A San Francisco County judge ruled tentatively Monday that Barry Bonds' 73rd home run ball must be kept under lock and key until an ownership dispute is settled.

San Francisco Giants fan Alex Popov temporarily caught the ball Oct. 7 at Pacific Bell Park, but lost it after fans piled on top of him during a brief skirmish. Days later, he sued Patrick Hayashi, who wound up with the ball that could fetch an estimated $2 million.

On Nov. 20, Popov and his lawyer Martin Triano filed papers with the court, which included declarations of 12 individuals who witnessed Popov catch the ball.

"We are delighted with this decision," Triano told ESPN.com's Darren Rovell. "We look forward to getting the ball back in the future."

Superior Court Judge David Garcia's order is a tentative ruling, meaning Hayashi's attorneys can challenge it at a hearing scheduled for Tuesday morning. If Garcia does not change his mind, the decision sets the stage for the nation's first trial over fan ownership of a ball hit into the stands at a major league stadium.

The injunction is needed because Popov believes that the selling of the ball would mean more than a monetary loss. While Popov filed papers that said if he was granted ownership of the baseball, he would not sell it, Triano said that it is clear that Hayashi means to sell it.

That's because Hayashi has retained agent Michael Barnes, who was responsible for selling the McGwire home run balls to Guernsey's Auction House, for that express purpose. Hayashi's lawyer Don Tamaki was not available for comment.

Last month, Garcia temporarily blocked Hayashi from selling the ball until he decided whether Popov's case could go forward. The ball was placed in a safe-deposit box at a San Francisco bank, with the court holding the keys.

The case is Popov v. Hayashi, 400545.

The Associated Press contributed to this report.