Aug.11 (GMM) As many as five of Felipe Massa's formula one race rivals could join the Ferrari star at his annual kart race in Brazil at the end of the 2008 season.

The 27-year-old championship contender's former teammate Michael Schumacher, who won the event in the southern city of Florianopolis last November, has already confirmed he will defend the title.

"To be honest, I didn't even have to invite him back. He told me at Hockenheim that he wished to race again," Massa said at a press conference in Brazil last week for the forthcoming 'International Challenge of Go-Kart Champs'.

2008 Toro Rosso racers Sebastian Vettel and Sebastien Bourdais are also likely to race, Massa revealed, as are Rubens Barrichello and Nelson Piquet Jr.

Robert Kubica, meanwhile, wants to attend on November 30 to make up for his absence last year.

"Almost everything was set for Kubica to race in 2007 but a last minute commitment prevented it," Massa explained.

NASCAR champion Jeff Gordon has also been invited, and Renault test driver Lucas di Grassi is also likely to race, the Ferrari driver said.