LOS ANGELES (AP) — Viacom's embattled chief executive sued Monday to be restored as a director and trustee to entities that control Viacom Inc. and CBS Corp. after a weekend move by media mogul Sumner Redstone stripped him of the positions.

Viacom CEO Philippe Dauman and lawyer George Abrams — who was also stripped of identical roles — filed the lawsuit in Norfolk probate court in Massachusetts, saying Redstone was "not mentally competent" and that he is being manipulated by his once-estranged daughter, Shari Redstone.

The question is key for Dauman. Without a board seat on theater chain National Amusements Inc., which controls 80 percent of the voting stock of Viacom and CBS, or a trustee seat in the trust which will receive the chain's assets when Redstone dies, his position as Viacom's CEO is in jeopardy.

The lawsuit's central claim is a change from six months earlier, when Dauman testified that Redstone was "engaged and attentive" during a 90-minute visit to his home. Back in November, Dauman's testimony helped Redstone fend off a suit by his ex-girlfriend, who claimed Redstone was incompetent when he threw her out of his home last fall and cut her from his will.

Dauman and Abrams say in their lawsuit that Redstone has rapidly deteriorated since then.

Redstone's attorneys responded Monday with a separate lawsuit asking Los Angeles' Superior Court to affirm Redstone's right to have made the changes stripping Dauman and Abrams of their positions.

The lawsuits are the latest salvos in a legal battle over the fortune amassed by Redstone, who turns 93 on Friday and requires a feeding tube along with round-the-clock care to stay alive.

Dauman's tenure has been increasingly criticized for falling viewership at networks like MTV and Nickelodeon and poor performance at movie studio Paramount Pictures. Viacom shares are about half the level they were in July 2014. They rose around 3 percent Monday.

Redstone's weekend action against Dauman and Abrams came less than two weeks after a Los Angeles judge threw out a mental competency suit by his former girlfriend, Manuela Herzer.

That trial was cut short after the judge viewed sealed video testimony from Redstone in which he repeatedly called Herzer an expletive. Herzer vowed to appeal and filed a new suit for at least $70 million against Shari Redstone, alleging that she illegally interfered with her inheritance by using a "spy network" of nurses to find ways to oust Herzer from the home.

That trial was over who would be Redstone's health care proxy.

But the stakes of the weekend's actions are far more financially important, since they pertain to control of Viacom and CBS themselves, media conglomerates collectively worth nearly $40 billion.