Brown is suing the OneRepublic star, claiming he gave Diplo a beat they had been working on for months, without permission.
According to the new lawsuit, obtained by TMZ, Zac claims he started working on the song, titled "Nowhere Left to Go", with Ryan in March 2018 and had an understanding that he would have ultimate control of the track.
But the following June, Tedder informed him he had given Diplo the OK to use the beat to create a different song, and the songwriter's manager asked Brown to delay his version.
Brown ignored the request and released "Nowhere Left to Go" on his first solo album, "The Controversy", last month (September 2019).
Zac claims Tedder submitted a takedown notice claiming the song infringed on his copyright, and now he wants the court to declare he owns the song and award him damages.