Goalkeeper Iker Casillas has insisted that Spain are under no illusions that they will walk into the Euro 2012 semi-finals if they meet England in the quarter-finals.

The Three Lions will go head to head with the reigning champions if they finish second behind France in Group D this evening.

While Spain are the favourites to retain the trophy, Casillas believes that England are capable of causing an upset.

"We've watched England's games and, like many sides, they're a country that has a good record," the London Evening Standard quotes Casillas as saying.

"They're strong, young and ambitious and we can't relax or assume that we'll go through. Any team can knock you out."

Spain secured their place at the top of Group C following a 1-0 win over Croatia.