Frank McCourt lost a critical round in his effort to maintain control of the Dodgers on Tuesday, when a judge invalidated an agreement that would have provided him with sole control of the storied baseball team.

As Frank McCourt's attorneys pledged to fight another round in court, Jamie McCourt's attorneys proclaimed her a co-owner of the team and hinted that she might soon challenge her ex-husband to sell the Dodgers to her and other investors.

David Boies, an attorney for Jamie, said he hoped Frank would agree to a settlement.

"I think the only way he could do that is to sell the Dodgers, either to her or to somebody else," Boies said.

In court papers, Frank valued the Dodgers at about $800 million; Boies estimates the value at about $1.1 billion, taking into account future broadcast rights and stadium land development.

Frank's attorneys said Tuesday's ruling conferred no ownership rights upon Jamie and would simply force Frank to use another legal means to establish the team as his sole property.

"What this means for Frank is a bit more time at the courthouse," attorney Victoria Cook said. Frank's lawyers contend that they can prove by virtue of the fact that the Dodgers are held in his name, he is the sole owner.

However, two family law attorneys consulted by The Times said Frank had played his strongest legal card and lost.

"To use a baseball analogy, this is like there are two out in the bottom of the ninth," said Lisa Helfend Meyer, a Century City family law specialist. "He really has no leverage."

Major League Baseball Commissioner Bud Selig declined to comment. The Times reported in September that the possibility of years of legal battles between the McCourts had prompted him to consider intervening on behalf of the Dodgers, but it is uncertain what options he might contemplate.

The ruling is not expected to have an immediate impact on the day-to-day operations of the team. However, the team could be in legal limbo for several more years.

Both Frank and Jamie on Tuesday spoke only through their attorneys.

Sorrell Trope, an attorney for Frank, said his client has not decided whether to appeal Tuesday's ruling. Instead, Trope said Frank would move for a second trial in which he would claim the Dodgers are his sole property because he bought them using a company formed before marriage.

After more than a year of divorce proceedings featuring such revelations as the McCourts' side-by-side homes in Holmby Hills and Malibu, the Dodgers charging themselves millions in rent each year and the payments to Russian physicist Vladimir Shpunt for channeling positive thoughts to the team, the court ruling Tuesday was rooted in a fundamental legal factor.

Los Angeles Superior Court Judge Scott Gordon threw out the marital property agreement -- known by its initials as an MPA -- because it did not conform to California law.

"The court finds that the MPA was not a valid transmutation," Gordon wrote, citing a legal term for transferring what would otherwise be community property into the sole property of one spouse or another.

That could be disturbing news at Bingham McCutchen, the Boston-based law firm that employed Larry Silverstein, the attorney who drafted the agreement.

Gordon wrote that Silverstein's admission that he switched a page of the agreement after the McCourts had signed it and without notifying them "is troubling and has introduced great challenges in this case. The evidence does not produce a reasonable explanation for Silverstein's exchange of such critical documents without notification or consultation of the parties."

Silverstein testified that his document switch merely corrected an error, replacing a page that specified the Dodgers were not Frank's sole property with one that specified they were, in accordance with what he said was the intent of the McCourts.