Tournament favourites Spain face the 2006 semi-finalists on Tuesday evening in Cape Town and, despite the quality Portugal possess, Ramos is delighted Spain managed to top their group after losing their first match to Switzerland.
"We hope the trouble we had in the group stage will make Spain a stronger team," he told Marca. "We are pleased with our performances so far and happy to have finished top in the group after the start we had."
"Portugal are a great team and they are in top form. I am looking forward to playing against team-mates and friends Cristiano Ronaldo and Pepe. Let's see if we can make it to the quarter-finals."
Ramos, who will come into direct combat with Ronaldo, believes that the key to beating Portugal lies in how well he can deal with the Real Madrid number nine.
"Cristiano is very fast, strong and a speedster with the ball at his feet. I have to prevent him from receiving the ball and we must stop him from having a lot of room to work with."
Ramos' team-mate Xavi also revealed he will be using advice passed on by Barcelona coach Pepe Guardiola to help deal with Ronaldo. Barca beat Real Madrid 1-0 at the Nou Camp and 2-0 at the Santiago Bernabeu last season.
"I remember perfectly (what Guardiola told us),'' the midfielder told Marca. "He told us to be careful with the balls played to him (Ronaldo) from deep and which he could run onto at speed.
"He told us to only allow him to receive short passes to feet and we had to mark him with help from team-mates, and cover each other, but never let passes be played to him from deep. That kills you. We marked him pretty well in both games.''
Xavi believes Portugal will sit back and look to hit Spain on the break with the pace of Ronaldo. "They will get men back, they will allow us to dominate and they will look for the speed of Cristiano, of Simao (Sabrosa),'' he said.
"Physically they are a strong team. Not only have they not let in a goal at the World Cup, but in their recent games they have only let in three - they are hard and aggressive.''
Xavi says Spain have the right personnel at the back to stop Ronaldo, but has warned his team-mates that Portugal are not a one-man team.
"Between (Gerard) Pique, Puyi (Carles Puyol) and Sergio (Ramos) he shouldn't be able to break free, but we must not become obsessed with him - Portugal is not just Ronaldo,'' he said.