Paula Abdul has accused former American Idol producer Nigel Lythgoe of sexually assaulting her when she was a judge on the show.
The singer’s lawsuit also accuses him of another assault, years later, when she worked on So You Think You Can Dance.
Lythgoe denied the accusations and said he is “shocked and saddened”.
Abdul claims the 74-year-old Briton groped her breasts and genitals and “began shoving his tongue down her throat” in a lift after a day’s filming in the early 2000s.
She said she pushed him away and ran to her hotel room when the doors opened.
Abdul called one of her representatives “but ultimately decided not to take action for fear that Lythgoe would have her fired from American Idol”, the lawsuit states.
The Grammy award-winning singer worked on eight seasons of the show before leaving in 2009.
A second assault allegedly happened around the time she joined So You Think You Can Dance, another of Lythgoe’s shows, in 2015.
Abdul claims he forced himself on her and tried to kiss her during a dinner at his Los Angeles home, but that she pushed him away and left.
The 61-year-old was on the judges’ panel with Lythgoe for two seasons of the dance show but hasn’t worked with him since.
The lawsuit also claims he taunted her about the alleged assaults, saying to her years later “they should celebrate” as “the statute of limitations had run”.
Abdul further alleges she saw Lythgoe assaulting one of her assistants on So You Think You Can Dance.
Lythgoe was a judge on ITV show Popstars – which created the band Hear’Say – when he was dubbed “Nasty Nigel” for his tough remarks on the series.
In a statement, he said he considered Abdul a “dear” and “entirely platonic” friend.
“While Paula’s history of erratic behaviour is well known, I can’t pretend to understand exactly why she would file a lawsuit that she must know is untrue,” Lythgoe said.
“But I can promise that I will fight this appalling smear with everything I have.”
Abdul filed the claim a few days before a California law expires allowing people a one-year window to sue over sexual abuse claims that have exceeded the legal time limit.
More than 3,700 were filed in New York – including claims against stars such as Axl Rose and Jamie Foxx – under a similar law that lapsed last month.