Moscow, Dec 2 (IANS): Coaches of top football nations Germany, Brazil and Portugal sounded a cautious note after the official draw for the 2018 FIFA World Cup was announced here.

Defending champions Germany have been placed along with lower ranked nations Mexico (16), Sweden (18) and Korea Republic (59) in Group F on Friday.

Title contenders Brazil have been placed with Switzerland, Costa Rica and Serbia in Group E.

European champions Portugal and 2010 FIFA World Cup holders Spain, Morocco and Iran have found themselves in Group B.

"This is a very interesting group of opponents. What we want to do in the group stage is set a foundation for the successful title defence. This is our goal," Germany coach Joachim Loew was quoted as saying by Marca.

Brazil coach Tite said: "More than evaluating the group, what I always have in mind is the evolution and consolidation of the team. These are top-class adversaries and that's why they are here."

Portugal coach Fernando Santos felt that the clash against bitter rival Spain may decide the group leaders.

"It's a very deceptive and treacherous group. Portugal have to accept that we are one of the favourites but if you look in a bit more detail, you can see it's very difficult. Spain are naturally favourites, as I've always said," he said.