Tens of thousands of protesters marched through central Belgrade, first under the banner of university students, then with Zajedno (Together), the opposition coalition. By late afternoon, thousands of demonstrators were facing ranks of several hundred riot police who were intent on stopping the protesters from marching away from an opposition rally in Republic Square.
Zoran Djindjic, an opposition leader, urged the crowd to disperse peacefully. Most did so, but a hard core of about 200 stood firm, and some youths hurled stones.
As pieces of paving stones rained down, police pursued the youths. A strange game of hide-and-seek followed, as police chased a small group through the streets and beat those they caught. At least seven were treated at the students' medical centre. Police later withdrew from the streets, leaving an uneasy calm. Zajedno told people to meet in 32 neighbourhoods later in the evening, but not to try to converge on the city centre again.
Earlier, Vesna Pesic, one of the triumvirate leading Zajedno, had appeared on the platform yesterday, with a hand bandaged from the beating she took from riot police on Sunday night. The crowd in the square roared in approval as Ms Pesic, Mr Djindjic and Vuk Draskovic insisted the protests would continue until President Milosevic acknowledges Zajedno victories in the local elections held on 17 November. "Last night's violence shows Milosevic does not know what to do," Mr Djindjic said, as his colleagues suggested that violence might herald the imposition of a state of emergency.
The courts were supposed to rule, yet again, on the status of 14 city council races won by the opposition. Until now, legal rulings against the regime have carried no weight, but Ms Pesic said a state of emergency might be used to override any decision in Zajedno's favour. The violence has sparked international repercussions, drawing condemnation from Britain and an invitation from France to the Zajedno leaders.
Both London and Paris seem to have switched tactics, apparently calculating that public criticism of the Milosevic government and acceptance of a potentially viable alternative leadership in Serbia could do more to resolve the situation than maintaining direct links with the regime. As usual, there was no word from the Serbian government, except a report on state television, which said that the riot police had been forced to act because protesters were blocking traffic.
Aleksandr Tijanic, who resigned as Serbia's information minister because of the protests, does not expect his former boss to give in easily.
"I think [the use of police] was a small exercise to see if the police would follow orders, to see how they would behave, how the demonstrators would behave, how the media would react," he said yesterday. "I think it will be tried again." Mr Tijanic believes Mr Milosevic needs to use force to cling to power: "It would cost him too much to agree a political solution... he does not portray this as a political problem but as a problem of social order for the police to deal with." The last time Belgrade experienced a "social problem" was in 1991, when Mr Milosevic crushed demonstrations by sending tanks on to the street.
Sunday's attack was perhaps the worst example of state violence against peaceful demonstrators since 1991. The students, who have run parallel protests since the elections, were particularly angered by a police incursion into a Belgrade University building on Sunday night. At student headquarters, Dragan Ostojic, who was acting as security, described being beaten by the police as they tried to chase students into the building.
Mr Ostojic said he turned fire-hoses on to the police who, an hour before, had used water cannon against the protesters. Medical students at a makeshift first-aid centre treated more than 50 people - including some policemen - for minor injuries, and said they witnessed several arrests.
However, Zajedno leaders were upbeat yesterday afternoon. "We will express our readiness to persist, to show that there is no more fear of the police or the regime," said Miodrag Peresic, Mr Djindjic's deputy. "I think today is a turning-point," he added.
On the streets of Belgrade last night, protesters were waiting uneasily to find out whether Sunday night was just a one-off, or whether it was a taste of things to come.