Capello admits the timing of sacking Alberto Gilardino and replacing him with the Frenchman has confused him.
"Nothing surprises me anymore,” Capello told Gazzetta.
“Gila did great things last year and was seemingly bouncing back after a troubled start amid big sales and injuries. The timing, in particular, leaves me perplexed.
"He’s a guy I knew when he was very young in Milan, and we reunited at Juventus when he was a well-known champion. He’s always been intelligent and polite.
“I demanded his signing in 2005 to create a super midfield partnership with Emerson.
“I met Vieira while he was on the Crystal Palace bench. He did well in the first season. He comes from the Arsene Wenger and Arsenal’s school. That’s his idea of football.”
On potential tension between Vieira and Mario Balotelli, Capello added: “Balotelli has always loved moving with the ball at his feet, but not much when he had to do the same collectively. At this level in football, there is always time to make peace."