Lazio's problem in dealing with racism among its fans resurfaced on Sunday during a 6-1 win over Sassuolo. Derogatory chants were directed at visiting players Claud Adjapong and Alfred Duncan.
Adjapong was born in Italy to Ghanaian parents and has represented Italy Under-19s. Duncan is from Ghana.
The league's disciplinary panel closed Lazio's Curva Nord for the match against Cagliari on October 22.
Lazio will also be without fans in that section when Udinese visit on November 5, as it was also decided to apply a sanction that had been conditionally suspended for racist chanting during the Rome derby on April 30.
Lazio has been fined and subjected to stadium closures for years due to racist incidents.
Last week, Lazio beat Belgian side Zulte Waregem 2-0 in a Europa League match behind closed doors due to punishment from UEFA for racist chants aimed at a Sparta Prague player in the Roman side's last continental appearance two seasons ago.