By Andrew Downie
SAO PAULO, (Reuters) - Avai fans broke the security fencing surrounding the pitch and forced police to intervene on Sunday after the referee awarded a late penalty to Sport in their 2-2 draw.
The spot kick came in the second minute of injury time and allowed Sport to salvage a point and retain their unbeaten record after 11 games.
"Fans of the Avai Futebol Club broke an acrylic panel used as a fence (surrounding the pitch) forcing police to form a barrier as a security measure," the match referee wrote in his report.
"As we were heading into the tunnel, a battery was thrown at the four officials from the area where Avai fans were located and hit the police shield."
The Recife-based team fell into third place, joint top on points with leaders Atletico Mineiro and Gremio, but they are still the only unbeaten side in the 20-team Serie A and are enjoying their best ever start to a league season.
Four of the weekend's 10 matches were away victories, with 3-1 wins for Atletico Mineiro at Internacional and a similar 3-1 triumph for Gremio at Santos lifting them into joint top.
Palmeiras defeated Ponte Preta 2-0 in Campinas to record their third win in a row, while Figueirense scored a late winner to give them the points in a 2-1 victory over Flamengo at the Maracana.
Vasco da Gama remained in the relegation zone after losing 1-0 at Chapecoense, with Santos joining them after losing for the third match in a row.