Brazil 2014: Black Blocs to provide black mark?

Story highlights

Leading professor cautions that protest groups may target buses and hotels of World Cup teams

'Black Bloc' groups have often been blamed when protests have turned violent

Coach Luis Felipe Scolari has previously said the protests may harm Brazil's World Cup hopes

CNN  — 

It’s not just fans traveling to the World Cup who should be worried about the looming demonstrations – but the players too, says a leading researcher into one of Brazil’s main protest groups.

Even though millions took to the streets to campaign against social injustice during the 2013 Confederations Cup, the protests at this month’s finals are expected to be both bigger and more violent.

While the vast majority of demonstrators will do so peacefully, a hard core element will be represented by a group commonly referred to as the ‘Black Blocs.’

Read: World Cup protests hit 18 Brazilian cities

Regularly clad in masks, balaclavas or bandannas, their behavior – which often includes smashing windows, damaging buildings and committing arson – has become common to Brazilians during the ongoing protests.