Magnus Karlsson has completed the line-up for his testimonial on Saturday by bringing in former team-mate David Howe and Swedish star Linus Sundstrom.
The meeting at Leicester's Beaumont Park has attracted a field with several of the sport's top stars to mark Karlsson's decade in British racing.
Howe said: "I would have been a little bit offended if he hadn't asked me.
"We spent a lot of time together at Wolverhampton and Scunthorpe, and we always got on fantastically well."
How added: "I very much enjoyed riding in the same team as him, I'm pleased he's got a testimonial and I hope it all goes well for him."