Germany defender Per Mertesacker has revealed that he is expecting a tough match when his team face Ghana on Saturday evening.

Joachim Low's side thrashed Portugal 4-0 to take control of Group G, while Ghana conceded a late goal to USA to fall to a 2-1 defeat.

However, despite their contrasting fortunes, Mertesacker, who will win his 100th cap in Forteleza, has insisted that his team can't afford to be complacent against the Black Stars.

The 29-year-old told the Germany Football Association website: "I think African teams, in general, play very physically. They also have an incredible strength in one-on-one situations.

"I think that is part of their mentality. They are very dangerous so we have to play very, very clever tactically. We should try to avoid those one-on-one fights."

Victory for Germany would all but secure their place in the last 16.