The two old Italian giants meet on Sunday evening after undergoing different starts to the 2018-19 campaign.
Juve are top of the league and unbeaten, winning 10 games and drawing one, while Milan are fourth, having won six games and lost two, as well as drawing three, of their opening 11 matches.
Ronaldo has played a major role in Juve's success thus far, scoring seven goals and providing five assists in just 10 outings, and Capello, who has played for and managed both sides, expects the Portuguese to make a major impact on the encounter.
“I expect great things from the most anxiously-awaited player: Cristiano Ronaldo," he told TuttoJuve, per Football Italia.
Juve lost in Europe in midweek, as they fell to a late 2-1 defeat to Manchester United.
Capello, though, believes the Bianconeri are the favourites, despite the defeat, though he admits that former Juve striker Gonzalo Higuain could be his ex-employer's undoing.
"Despite that defeat, Juventus arrive at San Siro in great shape and I don’t see any particular problems within Max Allegri’s team,” Capello added.
“It’s going to be an interesting game in so many ways. The Bianconeri have had a few more days to rest and are the favourites for the victory.
“Milan have some players who can cause problems for Juve, in particular Suso and Gonzalo Higuain if he recovers in time.
“However, the biggest issue is not how much pressure Milan could put on Juventus, but rather Juve’s own concentration levels at San Siro.”