MONTREAL - On one side of the barrier they shouted about the injustices of global capitalism; on the other they sipped beer and snapped pictures of luxury sports cars.
A group of activists protesting capitalism in general and Quebec's tuition hikes in particular have been trying their hardest to crash the party on the Montreal street most closely associated with this weekend's Canadian Grand Prix festivities.
There have been some surreal scenes as these two ideological worlds collide.
From the civil conversations to the brief fistfight, the last two nights have written a memorable chapter in the history of Crescent Street the most notorious party strip in a town that loves its parties.
Crescent has long been a spiritual home to the city's old-time scenesters, the silk-shirted dance divas looking to see and be seen ever since the days of disco.
This weekend it is the epicentre of another phenomenon: Quebec's ongoing ideological struggle.
Protesters haven't gotten as close as they'd like.
While thousands of Formula One fans flocked to Crescent as they do each year for the expensive cars, free swag and popular nightclubs, the demonstrators were kept at bay by lines of riot police.
As the marchers massed on the outside looking in, the party people inside cranked up the dance music to eardrum-rattling decibel levels to drown out their chants Friday night.
Some protesters danced on the edge of the police perimeter as a Lady Gaga lullaby shook the night. One got into an exchange of fisticuffs with a burly pedestrian who tried to take their picture. One was arrested for trying to run around the police line.
The police lines also left some frustrated tourists stranded on the edges of the F1 street party, waiting to get in. Instead, they witnessed things like riot police pepper-spraying and arresting people, as some protesters tossed bottles and other projectiles.
It was a similar scene the previous night.
A protest march that began near a community center in one of the city's working-class neighbourhoods marched its way to Crescent on Thursday, chanting an ethos not commonly associated with the land of two-for-one shooters and heavy cologne.
"1,2,3,4, this is fing class war," the crowd of several hundred chanted Thursday. "5,6,7,8, overthrow this fascist state."
Sunday's Formula One Grand Prix race, and the events leading up to it, traditionally mark the beginning of Montreal's festival season. The well-heeled Grand Prix crowd can bring in as much as $100 million for the local economy.
It comes at a vital time this year for the city's merchants, who blame the student conflict for lower-than-average sales.
But the importance accorded the race by public officials, especially the Quebec government, has made it a target for the student movement and its supporters.
With negotiations stalled and nightly demonstrations dwindling in size, they have turned the Grand Prix into a fault line in their battle.
They see the conspicuous consumption and flashy cars associated with the event as an insult against their ideals of a more egalitarian society one characterized by cheap university tuition.
On two consecutive nights, when demonstrators arrived at Crescent Street, they were blocked by a line of riot police.
Behind the line, it was like a parallel universe: revellers were either indifferent to the protesters, or muttering angry things about them, or approaching the police line out of curiosity and snapping pictures of the crowd clad in red squares.
The protesters' chants were barely audible over the thumping dance music. A brief but intense struggle with police erupted when the numerous demonstrators tried to force their way onto the crowded street Thursday.
Police immediately pushed them back with a heavy dose of pepper spray. Several protesters were arrested, including a few who were thrown down violently or dragged across the pavement. Some sustained shots with billy clubs.
Some tried in vain to get their message across to the Crescent crowd.
One young woman castigated police officers at the top of her lungs for what she called their "brutality." A patron sitting on an adjacent bar patio looked over and said simply: "keep it down."
Inside Grand Prix events, people were offering similar views. Former Grand Prix champion Jacques Villeneuve, who used to own a posh restaurant on Crescent, called the protesters "rebels without a cause" Thursday in remarks he says have since drawn threatening emails.
Protesters say their cause includes fiscal policies that favour funding for events like the Grand Prix, and corporate subsidies, while forcing students to pay more.
With the initial protest fragmented by police action, some activists took to blocking the intersections near Crescent Street on Thursday. Different world views collided there, too.
One frustrated passenger jumped from the Mercedes he was riding in and began arguing with the demonstrators Thursday.
"We just want to get by," he said after several minutes of angry gesturing.
He was told he would have to wait until protesters were done with the intersection. The crowd then began to chant: "Whose streets? Our streets."
Other demonstrators had more civil conversations with Grand Prix fans, though they didn't end with any sudden conversions either.
One exchange on Crescent Street had students trying to convince an elderly couple of the difficulties of graduating with more than $10,000 in debt.
"You don't get it," the man said, shaking his head. "You have to work."
At one point in the exchange, the decibel level of the voices rose. Tensions threatened to flare. A burly student finally cut everyone off.
"We're not going to convince you," the student said, "and you're not going to convince us."
-With files from Peter Rakobowchuk
Note to readers: This is a corrected story. An earlier version wrongly said Jacques Villeneuve currently owns a restaurant on Crescent Street.