In a new interview at The Zach Sang Show, UK singer Ed Sheeran shared an interesting story he heard from Rick Rubin about the first time Eminem and Kendrick Lamar worked together on “Love Game,” a collaboration for Em's album The Marshall Mathers LP 2. According to Sheeran, Em made sure that when Kendrick came to write his verse, he didn't have any help.
"I heard a very cool story about Eminem and Kendrick Lamar. Eminem...heard that Kendrick Lamar was the best rapper and he invited him to the studio to get him on a song. He arrived and Kendrick came with all his mates and Eminem said, 'I just want you in the studio, just you on your own. And then my engineer is gonna come in and then record you doing it. But your mates aren’t allowed in."
"Everyone came in to listen to it and Eminem said that he did it to test Kendrick because he thought he had a ghostwriter" Sheeran explained. "He then realized that he didn’t" after after he saw Kendrick write his "Love Game" verse with his own eyes, he was willing to call Kendrick "the best."
You can hear Sheeran tell the story himself at around the 7:50 mark of the video below.