Hizbul Islam and another group, al-Shabaab, which are widely seen as al-Qaeda's proxies in the region, control large swaths of the country and much of Mogadishu.
The groups enforce their own strict interpretation of Islam, routinely banning sport, music and dancing.
"Hizbul Islam unexpectedly knocked on our doors. They jumped over our wall. It was midnight and my two sons and others from the neighbourhood were watching the World Cup," Ismail Sidow, a resident, said.
Some residents in al-Shabaab-controlled areas are furtively watching the world's biggest sporting event, which is being staged in Africa for the first time, using makeshift satellite dishes to capture foreign broadcasts from South Africa.
"The first goal of the World Cup (scored) by South Africa is itself very great - we should be proud of it," Mohamed Muhidiin Xute, a member of Somalia's Football Federation, said.
Three years of fighting in the anarchic Horn of Africa nation has left 21,000 people dead and forced 1.5 million from their homes.
Only small pockets of Mogadishu pital remain in the hands of a UN-backed government and African Union peacekeepers.