At least 24 people were wounded in the blast, according to police and medics.
The violence is part of a trend of increasing militant attacks since the start of the year, which claimed more than 1,000 lives in May alone, making it the deadliest month since the sectarian bloodletting of 2006-7.
In recent days, men playing in local soccer fixtures and watching matches have been the targets - after spates of attacks on Sunni and Shi'ite mosques, markets and the security forces.
The reason for targeting soccer players is not clear.
Concerns that Iraq may lapse back into full-scale sectarian conflict have mounted in recent months amid tensions fueled by the civil war in neighboring Syria, where mainly Sunni rebels are fighting to overthrow a leader backed by Shi'ite Iran.
Sunni insurgents, including al Qaeda's Iraqi affiliate, have been regaining ground, recruiting from the country's Sunni minority, which resents Shi'ite domination since the U.S.-led invasion that toppled Saddam Hussein in 2003.