Ronaldo feels 'very positive' ahead of his World Cup campaign with Portugal

"We are coming into this tournament with great optimism," said the five-time Ballon d'Or winner.

"The build-up has been excellent, though exhausting, as we have put in a lot of effort," added the experienced Portugal captain, who maintained he felt "in good physical shape".

"I am very confident. I think everything will turn out well and that we will deliver a strong display.

"This is a very talented generation... one that will bring much happiness to the Portuguese people," the striker said of his teammates.

"The key is to get off to a good start in our first game, then follow that with the second and third... top our group and from there, approach each match as it comes."

Portugal begin their World Cup campaign on June 17th in Houston against the Democratic Republic of Congo, followed by matches against Uzbekistan and Colombia in Group K.

At the age of 41, Ronaldo will be appearing in his sixth World Cup, a record, but some have expressed worries that his involvement might hinder the progress of Roberto Martinez's talented squad.

Portugal recently played two friendlies against Chile and Nigeria, winning both 2-1, but Ronaldo did not find the net.

Portugal came third in the 1966 World Cup and made it to the quarter-finals four years ago in Qatar.