UPDATED: More shots were fired in the battle for control of Viacom on Monday, as CEO Philippe Dauman and director George Abrams urged a Massachusetts judge to approve an immediate medical evaluation of Sumner Redstone.

The two men are challenging their removal from the Redstone family trust and the board of National Amusements, the movie theater company that owns controlling stakes in Viacom and CBS. They contend that Sumner Redstone is not mentally competent to oust them from the trust and was manipulated into doing so by his daughter, Shari Redstone.

“Time is of the essence,” according to the latest legal filing, painting a portrait of Redstone as a man who is near death. The mogul suffers from dementia, and is unable to stand, walk, read or eat on his own, according to the filing, which claims that Redstone was recently hospitalized.

“The life expectancy of a reasonably healthy 93-year-old man is limited and unpredictable,” write attorneys for Dauman and Abrams. “The life expectancy for a 93-year-old with such serious health conditions is even more limited and unpredictable.”

“There is grave risk that Sumner Redstone will not be available to provide any evidence in this case,” they add.

As Redstone’s health declines, Shari Redstone and Dauman have found themselves in opposing camps. Their hostility spilled out into the open last winter, after Shari Redstone opposed Dauman’s elevation to the chairmanship of Viacom.

Dauman was once among Redstone’s most trusted lieutenants, a man that the Viacom mogul routinely praised on earnings calls as the “wisest” person he’d ever known. However, his tenure atop Viacom has been sharply criticized by investors and analysts.

The media company’s cable properties, a group that includes Comedy Central, MTV, and Nickelodeon, have taken ratings hits. They have been hurt by the loss of top talent such as Jon Stewart and the migration of younger viewers to online platforms. At the same time, the company’s film studio, Paramount, has also suffered declining market share after a period when it slashed the number of films it releases. It now is attempting to increase its output, but is struggling to compete with rivals such as Universal and Disney that boast better franchises. Dauman is trying to orchestrate the sale of a minority stake in Paramount, something that attorneys for Redstone say he opposes.

Last week, Redstone’s camp released a statement that the mogul believes Dauman is doing a “bad job” of running Viacom. The opinions were offered during May 20 and May 24 examinations by Dr. James Spar, a geriatric psychiatrist, who told the court that he found Redstone to be “alert and in no distress.”

In Monday’s legal filings, Dauman and Abrams’ team argues that Dr. Spar’s examination was flawed, calling it “one-sided, uncross-examined and distorted.” They note that the doctor’s account of the examination reads like an interview, despite the fact that Redstone is unable to “meaningfully” speak.

Redstone’s advisory team hit back, noting that Dr. Spar has authored books and articles on mental capacity and saying that the doctor will be deposed if the case proceeds.

“Sumner Redstone is physically stable, engaged with legal counsel, and participating in strategic decisions,” Redstone’s advisory team said in a statement. “He’s making his views clear, as Dr. James Spar indicates in his report filed with the court…We look forward to upcoming legal proceedings, so the truth can come out.”

Last week, Redstone’s camp said that a majority of trustees had approved the removal of Dauman and Abrams from the trust, but attorneys for the Viacom CEO and the director say their ratification has no legal significance. Only Sumner Redstone can make that decision while he is alive.

“The Trust instrument in no way provides that anyone else, including any of the trustees, has the power to remove trustees at a time when Mr. Redstone lacks capacity,” the filing reads.

Calling Shari Redstone, the mogul’s “estranged” daughter, the Dauman and Abrams filing goes on to assert that she is attempting a power grab. Redstone wanted “independent and professional management” of his companies, the men contend. The vote by the trustees is an attempt by Shari Redstone “to achieve the very control of the companies she was long denied,” the filing claims.