Juventus teenager Moise Kean appeared to suffer racist abuse after scoring a late goal to give the Turin side a 2-0 win at Cagliari in Serie A on Tuesday.
Kean, born in Italy to Ivorian parents, turned in Rodrigo Bentancur's cross with five minutes left and then turned to the Cagliari fans behind the goal and folded his arms.
In response, Cagliari's supporters made the noise which is described by Italian media as "buu" and is regarded as a racist insult in Italian football. Monkey noises could also be heard among the crowd.
Shortly after the goal, Juve's French midfielder Blaise Matuidi protested furiously to the referee and at one point appeared to threaten to walk off.
Matuidi complained last year that he was subject to racist abuse at the same stadium and Cagliari later apologised.
Play was halted for around three minutes and a warning was broadcast to the crowd -- the first step in the so-called three step procedure which ultimately leads to the teams being led off the field.
Play resumed amid more booing and the referee blew the final whistle shortly afterwards.
Defender Leonardo Bonucci had opened the scoring with a towering header from a corner in the 22nd minute.
The win took Juventus on to 81 points from 30 games with second-placed Napoli 18 points behind ahead of their game at Empoli on Wednesday.
Juventus were again without Cristiano Ronaldo who is recovering from a thigh injury he suffered playing for Portugal a week ago.