The Spaniards beat the Netherlands in the final of the 2010 edition to win their maiden World Cup, before lifting the Euro title two years later.
"Why has Germany not won any big titles in the last few years? I think there is one reason and it is called Spain. If Spain win the World Cup again that would make them the best ever national team. But I do not expect them to win it again," Lehmann said.
Uncapped duo Ander Iturraspe and Daniel Carvajal have both been included in Spain's 30-man provisional World Cup squad, along with Fernando Torres, but Real Madrid pair Alvaro Arbeloa and Isco have been omitted.
Lehmann, who was voted UEFA Club Goalkeeper of the Year for the 1996-97 and 2005-06 season, has been part of three World Cup squads during a successful career.
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On his country's chances in the mega-event in Brazil, Lehmann sounded optimistic.
"Germany is always ready to give you a hard fight at the end of a tournament.