Powered by four-times world player of the year Cristiano Ronaldo, Portugal kick off their Group A campaign on Sunday against Mexico in Kazan.

"This will be a very difficult competition, but Portugal are still going as title contenders," insisted the 62-year-old at a press conference near Lisbon.

"We always assume our responsibilities, tackling each game with the intention of winning it.

"A year ago I said that Portugal were going to Euro 2016 to win it. I said we were not favourites, but contenders for victory. I keep that same confidence today."

New Zealand and hosts Russia complete Group A for the World Cup warm-up tournament that runs from June 17 to July 2, with world champions Germany, Chile, Cameroon and Australia making up Group B.