Midfielder Zvonimir Vukic and striker Marko Scepovic scored second-half goals for the leaders to stretch their unbeaten league record against Red Star to nine games.
"We came here to win and got the result we wanted because we were more relaxed. Red Star were under much more pressure," Partizan coach Aleksandar Stanojevic told a news conference.
The first half failed to produce many fireworks on the pitch but there were plenty off it as both sets of fans hurled dozens of flares on the athletics track and forced two 10-minute delays in freezing weather.
The kick-off had been held up after Red Star supporters set off fireworks, with smoke billowing around the Marakana stadium and forcing much of the crowd to cover their faces with scarves.
A fire crew also had to extinguish a blaze on the track section in the fourth minute as Partizan fans replied with their own pyrotechnics.
Rival players and staff were then involved in a touchline brawl on the half-time whistle while the Partizan team were left in the dugout during the break, having refused to enter the tunnel after Red Star supporters hurled firecrackers at them.
During the week Red Star, who are second in the table with 29 points from 13 games, removed all seats from the south tier of the stadium due to safety concerns.
Newspapers splashed photos of seats being dismantled in the 55,000-capacity stadium where rival fans often rip them up during derby matches.
SUPERB GOALS
Red Star dominated the opening half and Brazilian midfielder Evandro wasted their best chance when his 40th-minute penalty struck the post.
The miss turned the game Partizan's way and the visitors, chasing a record fifth successive league title, delighted their followers with two superb goals.
Vukic sent the away end into raptures when he weaved his way past two defenders and rifled in a crisp low shot from 12 metres after good work by Scepovic in the 71st minute.
The robust provider turned scorer seven minutes later, taking a long through ball in his stride and poking it past advancing keeper Boban Bajkovic having raced beyond his marker.
"The half-time scuffle broke out after my counterpart Robert Prosinecki mistook my complaints to the referee over the penalty for something he thought I might have said to him," said Stanojevic.
Prosinecki, who as a player won the European Cup with Red Star in 1991 and took over as coach last December, acknowledged his team faced a mammoth task to wrestle the league title away from their bitter foes.
"Unfortunately all I can do now is congratulate Partizan. It's going to be very difficult to catch up with them because this is a hard defeat to swallow," he said.
"We are behind Partizan in terms of quality. We have to dig in and work much harder to break their stranglehold of domestic trophies."
