• by Joe Mandese  @mp_joemandese, June 20, 2014

CANNES, FRANCE -- Sir Martin Sorrell took the stage effectively, albeit jokingly, renouncing his knighthood. “I’ve taken Brazilian citizenship,” Sorrell quipped, adding that Brazilian soccer legend Pele “is my new friend.” Sorrell, who wore a bright yellow t-shirt signed by the soccer star, implied it was due to England losing last night’s World Cup soccer game with Uruguay.

Sorrell, who moderated a discussion between Twitter’s Dick Costolo and Viacom’s Philippe Dauman, also took a jab at rivals Omnicom and Publicis for their recent ill-fated “merger of equals,” focused mainly on the differences and commonalities between the digital-first and the legacy media giants.

After citing the impressive market valuations and financial stats associated with Twitter’s recent IPO, Sorrell noted that WPP’s GroupM will double its spending with the microblogging platform, boosting its ad spending from $50 million last year to $100 million this year. Based on Sorrell’s figures, that means GroupM contributes nearly a fifth of all of Twitter’s advertising revenues.

Despite that, he said he was “a little confused” about what Twitter actually is, and implied it is “morphing into something else."

“What is Twitter going to be? Is it going to be an amalgam of a number of other platforms?” he added, asking Costolo to define it.

“We think of Twitter as the best way to keep up with the world,” Costolo said, and cited an array of ways it does that, including “amplifying” content produced and distributed by companies like Viacom, providing metrics on audience engagement and developing a new form of “in-moment commerce.”