Inter Milan's 2-1 win at Cagliari was marred by another racist incident at the Sardegna Arena in their Italian league game on Sunday.
Romelu Lukaku converted Inter's winning penalty kick in the 72nd minute and then glared at home fans behind the goal as they had been racially abusing the former Manchester United player.
Everton forward Moise Kean, who is also black, was subject to racist abuse when he played against Cagliari for Juventus last season, as was Blaise Matuidi the year before.
Sunday's latest incident took the gloss off what was Lukaku's second goal in as many games for Inter and the team's second straight win under Antonio Conte after last week's 4-0 victory over newly-promoted Lecce in the Nerazzurri's opener.
"I didn't hear it so I can't comment," Conte said when asked about the racist abuse. "But I can talk in general: I think that in Italy we have to improve, to respect everyone.
"When you're abroad there's more respect, the fans think only about encouraging their team."
Lautaro Martinez had given Inter the lead in the 28th but Joao Pedro headed in Nahitan Nández's cross five minutes into the second half to level.
Inter midfielder Stefano Sensi thumped a free kick off the crossbar but won the penalty shortly after when he was tripped by Fabio Pisacane.
DERBY DAY
A 1-1 draw in the Rome derby was an appropriate result amid unusual solidarity between normally warring supporters of Lazio and Roma following the shooting death of a high-profile fan.
Both ends of the Stadio Olimpico paid tribute to Fabrizio "Diabolik" Piscitelli, the former Lazio "ultras" chief who was shot dead at point-blank range in an unsolved murder last month.
Roma went ahead with a first-half penalty from Aleksandar Kolarov, after Edin Dzeko's effort came off Sergej Milinkovic-Savic's arm, and Luis Alberto equalized for Lazio after the break.
Despite stifling humidity, the match was highly entertaining and featured six shots off the woodwork — four by Lazio (Lucas Leiva, Ciro Immobile, Joaquín Correa and Marco Parolo) and two by Roma (both by Nicolò Zaniolo).
Lazio also had a potential winner from Manuel Lazzari disallowed in the closing minutes for offside.
OTHER MATCHES
Torino is the only team apart from Inter and Juventus to have maximum points from the first two matches after it beat Atalanta 3-2
Duvan Zapata scored twice for Atalanta, which finished third last season to qualify for the Champions League for the first time in its history.
Domenico Berardi scored three goals in a 14-minute span in the first half to help Sassuolo beat 10-man Sampdoria 4-1, while Hellas Verona won 1-0 at fellow promoted side Lecce.
Also, Genoa beat Fiorentina 2-1 and Parma won 3-1 at Udinese.
