Robert Llewellyn claims James Corden and Jerry Seinfeld ripped off his 'Carpool' idea.
The 'Red Dwarf' actor - whose YouTube series saw him chat to the likes of Jonathan Ross and Ade Admondson while driving in an eco-friendly car - has taken to Twitter to take credit for the popularity of the two stars' own takes on the format.
After Seinfeld revealed the trailer for the 11th series of 'Comedians In Cars Getting Coffee' - which first launched in 2012 - Robert tweeted: "This is only of any interest because the original 'Carpool'... started a full 3 years BEFORE Jerry and his pals copied it. LOL (sic)"
The 63-year-old star's original web series launched in 2009, before it debuted Dave the following year, while Corden's 'Carpool Karaoke' segment first aired in 2015.
Seinfeld replied on Twitter to apologize over the similarities between the shows, but he insisted he wasn't aware of Robert's own project.
He wrote: "Apology to Robert Llewellyn Carpool. Had not heard of it. (sic)"
Back in 2012, Llewellyn said he had "literally thousands of tweets" from fans encouraging him to sue Seinfeld over the series.
However, he later admitted: "The lawyers confirmed that we couldn't sue them and I wouldn't want to."
Meanwhile, Corden has previously pointed to a 'Comic Relief' charity telethon skit with George Michael in 2011 as the inspiration for 'Carpool Karaoke'.
He said: "A character in a sitcom that I wrote was driving George Michael to a meeting for Comic Relief, and we were singing Wham! songs in the car, and amazingly it just really resonated with people. People just really responded to it."
He explained the idea for the hugely popular skit came from a meeting with the 'Late Late Show' team.
He added: "When you're putting together a show like this, you're searching for the tentpoles that might prop up your show. So we came up with this thing, we're in L.A., people are talking about the traffic and how they get to work.
"I remember that conversation with myself and Ben, the executive producer of the show. He was saying, 'Maybe there's a way in which someone could help get to work,' and Ian Carmel said, 'In the carpool lane.' I said, 'Carpool Karaoke.' And we all just went, 'Okay, that's it!' "