Germany defender Jerome Boateng has warned his side that Algeria will provide a tough physical test in their second-round clash at the World Cup.

Vahid Halilhodzic's side qualified for the knockout stage in Brazil after beating South Korea and drawing with Russia, while they sustained a narrow defeat to Belgium in their opening Group H game.

Boateng has admitted that he has been impressed with what he has seen from Algeria in the tournament and warned his teammates to take nothing for granted in their clash.

He told FIFA.com: "You sense huge determination and passion. The players have French roots, and many of them have come through the very good French coaching system. And I've seldom seen such a physically robust team.

"Their forwards are quick and the defence is strong. Algeria keep it very tight and they're smart tacklers. Anyone who believes we can start thinking about the quarter-finals already is making a big mistake. They have fantastic ability."

Germany take on Algeria in their last-16 match later today.