WELLINGTON, New Zealand - The composer of the opening guitar riff for Eminem's "Lose Yourself" says the soundtrack of a New Zealand political ad is a "blatant rip-off."

Jeff Bass told the High Court in Wellington on Tuesday that the song titled "Eminem Esque" that was used by the ruling National Party during its 2014 election campaign sounds like "Lose Yourself Lite."

But he added, "It doesn't taste so good, though."

Eminem's music publishers sued the National Party over the song, and the copyright infringement trial that started Monday is expected to last about six days.

Bass picked up an acoustic guitar and strummed the riff that opens the Oscar-winning 2002 song to eight lawyers and a judge while he was testifying. He lives near Detroit and travelled to New Zealand to testify.