Spain's 3-2 victory over South Africa confirmed top spot in Group B for them and a second-round clash against the Republic of Ireland.
Coach Jose Antonio Camacho said: "I think the knock-out phase will be open with a lot of goals and we will do our best.
"Ireland did not lose any games. They are a very compact team and we know it will be difficult.
The Spaniards, who have often under-performed at the World Cup, are the first team to go through with a 100 per cent record.
But Camacho said: "This is not a World Cup of surprises, it is a very equal World Cup.
"Argentina and France have gone home but if they had stayed they could have ended up contesting the final, who knows?"