Argentina legend Maradona says Germany`s powerful performance in their 4-0 win over Portugal is cause for concern amongst the other World Cup favourites.
"We saw a devastating Germany, a Germany who roamed around with perfection," the 1986 World Cup-winner told his Venezuelan television show "De Zurda".
"They caused a bit of worry with their physical strength."
Thomas Mueller became the first player to claim a hat-trick at Brazil 2014 as Cristiano Ronaldo`s Portugal were outclassed after centre-back Pepe`s first-half dismissal in Salvador.
Former Argentina coach Maradona got a taste of Germany`s power four years ago in South Africa when his team was hammered 4-0 in the quarter-finals.
Maradona said he was impressed by the Germans` "very, very intelligent lines of running" against the Portuguese in their Group G opener.
"If Germany keep this rhythm, then they must be taken seriously," Maradona added.
The Argentina legend has already nicknamed Germany`s hat-trick star Mueller `El Flaco` -- the Skinny One.
"He has no muscles, but today he tore them apart," added an impressed Maradona.