On Wednesday, it was reported that the Real Madrid ace was forced to sit out the rest of the competition amid claims that he would be risking his career if he played on.
However, Beto insists that Portugal's talisman is fully fit and raring to go ahead of his nation's remaining Group G fixtures with USA and Ghana respectively.
"Ronaldo didn't leave training early. He finished his training at the same time as the rest of the players," the shot-stopper told reporters.
"Cristiano is 100% fit to play. Every match he starts to play, it's because he's fit to play.
"He loves football but his body is the most important thing for him, to be fit, to be healthy so if he starts the match it's because he's ready, he's fit."
Portugal resume their World Cup by facing Jurgen Klinsmann's USA on Tuesday, kickoff for which is scheduled for 11pm.