Real Madrid's Ronaldo has been suffering since at least April from a form of chronic tendonitis in his left knee, and has admitted himself to playing through pain in order to feature in the most important games for club and country.
The 2013 Ballon d'Or winner was clearly hampered by the injury during Portugal's disappointing campaign in Brazil, scoring just once in the three games as Bento's side failed to progress from the group stage.
Bento said even before the World Cup started that Portugal's medical staff would "try and manage the condition" of the 29-year-old as well as possible, while national team doctor Henrique Jones said during the tournament that he was still below 100 percent but fit enough to play.
The issue is reportedly a major worry for Madrid, with reporters close to the Primera Division club suggesting Ronaldo could be making the problem worse by refusing to stop and rest, an idea the player himself has regularly rejected.
On his return to Portugal Bento told TVI that the national captain had not risked his fitness during the tournament, as Ronaldo had been "clinically" well enough to train and play as he had done.
"When he arrived he was not at 100 percent but then he was always able to train and play," Bento said. "He played with effort and sacrifice, but clinically he was able to play. If not, he would not have played. There was no type of pressure to speed up his recovery."
Reports from close to Ronaldo's camp say the player plans to now spend three weeks resting and working with personal physio Antonio Gaspar, and should be fine to join up with Madrid's squad when their preseason preparations begin in the U.S. on July 21.
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