There was no immediate claim of responsibility for the blast in the Nayi-Nama area of Damaturu last night but suspicions immediately fell on Boko Haram militants, who have previously attacked big screen venues showing matches.
Boko Haram, which in April kidnapped more than 200 schoolgirls in northeast Nigeria to international condemnation, has been waging a brutal, five-year insurgency that has claimed thousands of lives.
Local residents in Nayi-Nama said the bomb appeared to have been hidden in a motorised rickshaw outside the Crossfire venue, where crowds had gathered to watch tournament hosts Brazil play Mexico.
The blast happened at about 2345 IST, said Yobe state police commissioner Sanusi Ruf'ai, 15 minutes after the match kicked off in Fortaleza.
"We received 21 dead bodies and 27 injured victims from the blast," a source at the Sani Abacha Specialist Hospital in Damaturu, of which is the Yobe state capital.
Soldiers and police brought in the dead and injured from the scene of the blast, which was quickly cordoned off, the source said.
"The victims are young men and children. They have burns, ruptured tissue and bone fractures," he told AFP.
The blast was the latest in a series at football viewing centres in Nigeria blamed on Boko Haram, which has previously attacked schools teaching a "Western" curriculum and Christian churches.
Boko Haram leader Abubakar Shekau has preached against football as part of the Islamist group's agenda to impose strict Islamic law in northern Nigeria.
In several video clips, he described football and music as a Western ploy to distract Muslims from their religion.
In April this year, suspected Boko Haram gunmen also stormed a packed venue in Potiskum, also in Yobe, shooting dead two people as they watched European Champions League quarter-final matches.
Football is Nigeria's national sport and has a fanatical following but recent blasts targeting fans in northeastern Adamawa and the central state of Plateau have seen the authorities close big screen venues on security grounds.