The 'Derby della Capitale' is the most intense in Italy and while Sunday's clash at the Stadio Olimpico could have a direct impact on the sides' title hopes, for most it's a question of local pride.
"It's a rivalry that can give you pride for the whole year, keep the smile on your face and give you a chance to mock your rivals," Giulio Lucarelli told AFP.
As the owner of the Core de Roma restaurant, situated opposite the building where Roma icon Francesco Totti grew up, Lucarelli should know what he's talking about.
But while he has "respect for the fans of Lazio", you won't see any sky blue - the colours of the team nicknamed the 'biancocelesti' - in his establishment.
Instead, burgundy-coloured football shirts bearing the names of Totti, (Daniele) De Rossi and (Alessandro) Florenzi deck the walls in a permanent tribute to the side which, for the past 25 years, has been carried along by the goalscoring exploits of one-club man Totti.
Totti, in his 25th and likely final season with Roma, is not even sure to start on Sunday when both sides will be looking to maintain their early season challenge to five-time consecutive champions Juventus.
Between them, Roma (2) and Lazio's (2) respective title hauls fade in comparison to northern giants Juventus (32), AC Milan (18) and Inter Milan (18).
But in terms of same-city rivalry, Lazio-Roma is hard to beat.
"I was born anti-Roma," insists Patrizio Lillocci, who runs the family's official Lazio store selling the club's merchandise.
"I would say I'm even more anti-Roma than pro-Lazio. If Roma lose and Lazio lose, that's fine by me.
"My hatred for Roma is limitless. For me, it's the derby every day, every minute, every second."
'I watched them suffer'
For Patrizio, "May 26" immediately springs to mind when asked to recall his best footballing memory.
When Lazio beat Roma in the Italian Cup final on May 26, 2013, the joy for Patrizio was seeing Roma fans suffer.
"Their fans were devastated, and I watched them suffer," added Patrizio. "I wasn't happy we'd won, but because we made them suffer."
A thaw in relations between fans this past year was only because both were united against a rash of unpopular security measures introduced at the Stadio Olimpico.
Otherwise, it's business as usual.
The Lazio-Roma derby has been savoured by hundreds of players over the years, and former France midfielder Vincent Candela remembers only too well.
He experienced the joy of a crushing 5-1 win over Lazio in his time at the club, although it was followed by four consecutive derby defeats.
"For a player, it doesn't get any better," Candela told AFP. "Playing in front of 80,000 fans where, at one side of the stadium they whistle at you for the whole match while the other side adore you ... it's extraordinary."
At the Olimpico, Lazio's hardline fans occupy the Curva Nord (North End) while Roma's hardline 'tifosi' are in the Curva Sud (South End).
Tragically, that rivalry has spilled over: in 1979, Lazio supporter Vincenzo Paparelli was killed by a distress flare launched from Roma's Curva Sud.
Totti, and only Totti
When it comes to territory in the Italian capital, Roma have the edge. The 'Giallorossi' (Yellow and Reds) are more widely supported, but Lazio is the capital's original club having been founded in 1900, 27 years before four local clubs came together to form Roma under the aegis of the ruling fascist party.
"We were founded first and that pisses them off," said Guido, a Lazio supporter, after buying his ticket for Sunday's game.
In what was effectively a snub to former dictator Benito Mussolini, Lazio resisted the fascist party's attempts to fuse them with the other clubs in the capital.
But although Lazio have historical longevity, Roma have Totti. The club's reputation has been boosted immeasurably over the years by the 40-year-old icon known affectionately known as the 'King of Rome'.
The moniker is not exaggerated. From the auto garages of Monte Testaccio to the ice cream shops and bars around Trastevere, photos and murals of Totti are everywhere.
Totti has racked up an unrivalled tally of 41 derbies, won 14, lost 15 and scored an as-yet unbeaten 11 derby goals in the process.
In some of those, Totti provoked fans of Lazio most: notably lifting his shirt to reveal a message that said, 'I've purged you again', after scoring in a 3-1 Lazio win in 1999.
For Giulio Lucarelli, Totti's "special celebrations" mean only one thing: "For me, Totti is the derby."
But as derby fever intensifies, the Roma legend didn't miss a chance to add fuel to the fire.
Totti said: "Everyone is free to choose the team they want. Some are just luckier than others, that's all."
By Stanislas Touchot