Portugal striker Cristiano Ronaldo says he is not worried about his goal drought which saw him fail to net in the World Cup qualifiers because goals, he explained, are like "ketchup - when it comes out (of the bottle) it all comes out at once."

Ronaldo has not scored for his country in 16 months, since a friendly win over Finland, and drew a blank altogether in the qualifiers as his countrymen limped home with a play-off success over Bosnia. In the Spanish league, however, Ronaldo has netted 26 times for Real Madrid.

I am not worried - I am just plugging away as usual.

Cristiano Ronaldo, Portugal striker

"But I am not worried - I am just plugging away as usual. God knows who is working hard and who is deserving. I am perfectly calm. I want to turn in a great tournament and, who knows, be the best. I will strive for that. My ambition has always been to be the best."

The Portuguese open up their campaign against Côte d'Ivoire on Tuesday before taking on Korea DPR and Brazil.