In what many will consider an overdue reaction to racism in football, a black player is suing a white opponent over an alleged racist insult directed at him during a match in Belgium. Oguchi Onyewu, the United States and Standard Liege defender, has accused Jelle van Damme of Anderlecht of calling him a “dirty monkey”, a claim that Van Damme, who is white, has denied.

Accusations of racism made by black players against spectators and other players are far from uncommon, but Onyewu's recourse to law takes the battle a stage further. “He was convinced it was his duty to lodge the complaint,” Jean-Louis Dupont, Onyewu's lawyer, said. “It is not a question of whether Van Damme is racist. The issue is that these slurs are still used on the pitch, and are being used because they know it hurts.”

The alleged insult was used during the first leg of the Belgian league title play-off between Standard and Anderlecht on May 21. Onyewu, who is presently preparing with the US squad for the Confederations Cup in South Africa this month and two World Cup qualifiers, alerted the referee to three incidents during the match, but no action was taken. He threatened to leave the pitch but was convinced to stay by teammates. Standard drew the match, winning the second leg 1-0 to retain their league title.

Onyewu, who has 40 caps and had a spell on loan at Newcastle United two years ago, is seeking personal damages, but also, according to court papers, wants the case to help eradicate such behaviour in football. “A great many lesser-known African players don't have the stature to publicly denounce the insult they suffer on the pitch,” Dupont said. “With Oguchi, it is different.”

While clubs and even national teams have been fined for racist abuse by sections of their supporters, and individual spectators have been dealt with in courts, racism on the part of players has been harder to establish, even though the problem is a long-standing one. As long ago as 2000, Patrick Vieira, then an Arsenal midfield player, called for action against Sinisa Mihajlovic, the Lazio defender, following repeated insults in a Champions League match in Rome.

"When a fan does it, it is stupid but you can do something about it,” the France midfield player, who now plays for Inter Milan, said. “They can be identified. When a player does it, it is unbelievable but difficult to prove. It was the worst abuse I have ever heard, even when I have had problems in the Premiership it has been nothing like this. It never stopped from the moment the teams were shaking hands at the start.

"He did it in the first game at Highbury and I thought maybe it was just because we won the game that he was upset. I told him he'd said enough. What is really surprising is it has come from a player who is a foreigner in Italy. I asked some of the other Lazio players if they could hear it and they apologised and said he's stupid, he's always like that.”

By October 2006, Uefa had accepted the need to treat the problem seriously, as was proved by a five-match suspension imposed upon Nikola Mijailovic, the Serbian defender who was found to have made racist remarks to Benni McCarthy of Blackburn Rovers during a Uefa Cup tie between Blackburn and Wisla Krakow of Poland following a complaint by the Premier League club.

“It was a really important issue for us and I think we were right to highlight it to Uefa,” Mark Hughes, then the Blackburn manager, said. “Obviously we could not know just whether or not Uefa would come down as strongly as we hoped, but, in fairness, they have done.

“I think it helped because our complaint was against an individual - we had no problem with Wisla Krakow, the crowd was fine and the club itself were very accommodating. However, such individually-made comments have no place on a football field or in general life. The player has been punished and rightly so.”

Jason Roberts, McCarthy's teammate, believed that Blackburn had set an example by taking action in support of individuals. “Fair play to the club,” he said. “There have been other instances where clubs have not been as keen to take up such a cause, but Blackburn have proved they are fully behind their players. Things are starting to happen now and hopefully through this ban people will think twice about doing something like that in the future.”

After Onyewu's decision, racist players may not only have to think twice but also find a lawyer.