Dries Mertens has warned Belgium against the perils of complacency as they prepare to face Japan here today with one eye on a possible quarter-final showdown with Brazil.

The Belgians have emerged as dark horses at this World Cup, with their "Golden Generation" of players tipped to mount a deep run into the knockout rounds. Roberto Martinez's side defeated England 1-0 in their last outing to top Group G, earning what on paper should be a straightforward Last 16 assignment against Japan. But Mertens says the Red Devils are wary of a possible repeat of their Euro 2016 quarter-final, when they crashed to a 3-1 defeat to Wales despite being favoured to progress.