Iker Casillas believes Spain must play at the top of their game to beat Scotland at Hampden Park.
Craig Levein's side were defeated 1-0 by Czech Republic on Friday and have so far failed to impress in the Euro 2012 qualification campaign.
Scotland's only success to date has been a narrow 2-1 victory over Liechtenstein, while Spain sit top of Group I with maximum points from two games.
Having also won the World Cup over the summer, Vicente del Bosque's side are strong favourites to maintain their perfect record against Scotland on Tuesday.
However, Casillas insists there is no such thing as an easy match for Spain and is fully aware of Scotland's strengths.
"Any opponent that plays against Spain is trying to do their best to beat us," the Real Madrid goalkeeper told Marca.
"Everyone wants to brag about beating us, and we know the role we have to play. We must be 100 per cent.
"Scotland have some important squad players in their side, such as Darren Fletcher who commands the (Manchester) United midfield. We have to be prepared."