UEFA says it opened a disciplinary case against Lazio for ''racist behavior'' by fans which disrupted a Europa League Round of 16 match.
Lazio fans reportedly aimed racist chants at Sparta Prague defender Costa Nhamoinesu, who is black and from Zimbabwe.
The referee stopped play in the first half of a 1-1 draw in Prague on Thursday for a warning to be broadcast to Italian fans.
UEFA guidance on racial abuse requires referees to order public warnings as a first step toward possibly abandoning a match.
UEFA's disciplinary committee will judge the case on March 22.
Lazio was sanctioned several times in the 2012-13 season for fans' offensive behavior at Europa League matches.
Lazio hosts Sparta next Thursday in the second leg to decide who advances to the quarterfinals.
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