The Arsenal defender believes la Roja have the hunger to add another international title to their trophy cabinet later this month by going all the way in South America
The reigning world and European champions travel to Brazil in the coming days hoping to add yet another major trophy to their ranks.
And the Arsenal defender believes his Roja team-mates have an enduring hunger in international tournaments which gives them the edge over their counterparts.
Speaking to a press conference, he said: "During the two training sessions we have done in Miami it is clear this team is made up of people who will never get tired of winning.
"Physically we are feeling very good and the change of climate [training in the USA] has not affected us."
Meanwhile, David Silva, who flanked Monreal at the press briefing, says Spain will go into the Confederations Cup with the weight of expectancy on them.
"Spain will have the role of favourites, but Italy and Brazil are two great teams who will also be there," he added.
The Manchester City playmaker also took a moment to welcome Jesus Navas to England after he completed his move to the Etihad earlier this week.
"Navas is a great player who will come in very handy," he added. "I am delighted to have him as a team-mate next season."
Vicente del Bosque's men kick off their Confederations Cup campaign by hosting Uruguay on June 16.