Fans carrying iron bars got into a heated confrontation before the match that marked Robinho's return to Santos in the Brazilian league on Sunday.
Nearly 100 fans clashed before the match at the Vila Belmiro Stadium, where third-place Corinthians won 1-0 to move closer to leader Cruzeiro. It was Robinho's first game since transferring back to Brazil on a one-year loan from AC Milan.
Video footage showed fans swinging iron bars and throwing rocks and other objects at each other on the streets outside the stadium. Some Santos supporters aimed firecrackers at their rivals.
The clash apparently started after Santos fans ambushed Corinthians supporters as they tried to make it to the stadium in the coastal city of Santos. The fighting ended after outnumbered Corinthians fans started to flee. No major injuries were reported but at least 20 people were detained. A few cars parked on the streets were damaged.
Fan violence also was reported before Internacional's 2-0 win over rival Gremio in Porto Alegre, where police had to confront Gremio fans heading to the Beira-Rio Stadium.
With the victory, Internacional jumped to second place in the 20-team standings, two points behind defending champion Cruzeiro, which drew Criciuma 0-0 on Saturday to reach 30 points from 14 matches. Cruzeiro hasn't won in two rounds.
Chile midfielder Charles Aranguiz opened the scoring for Internacional with a header in the 62nd minute and Claudio Winck added to the lead after a pass by Argentine playmaker Andres D'Alessandro in the 85th in front of nearly 40,000 fans at the Beira-Rio.
Corinthians jumped to 27 points after defender Gil scored with a header off a corner in the 84th at the Vila Belmiro. Former Brazil striker Robinho, in his third stint with Santos, played well and had a few chances to score, but couldn't keep his team from losing at home.
Santos, ninth in the standings, played a man down the entire second half because midfielder Alison was sent off just before halftime.
Fourth-place Fluminense missed a chance to move closer to the leaders after a 1-1 home draw against Vitoria at the Maracana Stadium on Saturday.
Sao Paulo moved to fifth place by beating Vitoria 3-1 with two goals by former AC Milan striker Alexandre Pato at the Morumbi Stadium, while Flamengo defeated Sport 1-0 with a goal by recently signed Brazilian-born Croatia striker Eduardo da Silva at the Maracana. Brazil's most popular club remains in relegation zone despite the win, its second in three matches.
Also Sunday, Atletico Mineiro defeated struggling Palmeiras 2-1 with a late goal by Argentine striker Jesus Datolo. Palmeiras, coached by Argentine coach Ricardo Gareca, hasn't won in eight league matches.
On Saturday, Bahia ended a 10-match winless streak by beating Goias 1-0 at the Fonte Nova Arena in Salvador.