And at the heart of each samba school's troupe of performers - some up to 5,000-strong - will be the queen of drums, the dancer chosen to embody the rhythm and beauty that brings the procession to life.
For women like Bruna Bruno, 29, the four-day festivity that brings Brazil's biggest city to a standstill is also the high point of months of hard work and preparation for the role of drum queen.
"When carnival starts, I will be full of happiness and joy," the queen of Uniao da Ulha said. "I just want everyone to do a great parade."
But behind the exotic costumes and dancing that draws two million spectators on to the city's streets lies a less attractive side: the fierce competition between women for the coveted top slot, and between rival schools to be named best in their league.
Last week, the Brazilian press published photographs of the scars that some dancers bear from continuously sambaing down the Sambodromo, a specially built stretch of street lined with stands for spectators. They had callused feet from their high heels, bruises, scratches and, in one instance, burns from an accident in which a costume caught fire.
The gruelling training sessions endured by the women in the months leading up to the parade, which necessitate regular visits to the doctor for checkups, are just part of the picture.
Of all the intricate costumes worn by performers at the carnival, that of the drum queen is most revealing - putting pressure on the women to get themselves into shape by whatever means necessary.
The result is that Miss Bruno, who runs a beauty clinic by day, is widely reputed to be the only top drum queen not to have sought surgical enhancement for the role.
"There is a lot of pressure," Miss Bruno said. "But I prefer to maintain my body naturally, with exercising, diet and massage. I have had no surgery."
She has held on to the top spot with her school for nine years. Miss Bruno's samba school is based in Ilha do Governador, the island in Rio's Guanabara Bay that is home to the city's airport and 500,000 people, and is also where she was born and brought up.
It was always the tradition that each samba group's drum queen would be chosen, like Miss Bruno, from the local community, for her beauty and charm. But in recent years schools have begun to look further afield, with an eye to the publicity that the right drum queen can bring.
High-profile models, actresses and a former contestant in Big Brother Brazil have been selected in the past.
Among them is Susana Vieira, a popular Brazilian television actress, who was in her sixties when she was invited to be the drum queen for Grande Rio, one of the elite 12 that form the Special Group, or top league, of samba schools in Rio de Janeiro. Having already enjoyed a successful acting career, Ms Vieira commanded the attention of the public and the press despite her advancing years.
Now she has become the unexpected voice of many of those who worry about the direction that the carnival has taken and its effect on younger dancers.
"When you enter the Sambodromo for the parade, it's a big responsibility," she said. "It's very competitive: every beautiful young woman wants to be the drum queen as it's the role with the most visibility.
"I know the girls suffer a lot. For them, it's like a war. They live for this. For me, it's just one part of my life. I live to be happy, to be a great actress and a beautiful woman. But the women from Rio are preoccupied just with their bodies."
She blames in part the increasing commercialisation of the carnival, with rival schools requiring constant improvements to stay at the top of their leagues.
However, she is critical of the younger women for succumbing to the pressure to have surgical enhancement, in a country where, according to recent figures, the number of people seeking plastic surgery has doubled over the past four years.
"The women here in Brazil have plastic surgery very early," she said. "At 25 or 26, they put silicone in here, they cut there, and it's permanent. They shouldn't do this, they are young, so why do they need this?"
Many blame the attention lavished on Rio's drum queens for fuelling the demand for cosmetic surgery, making Brazil, where 905,000 procedures were carried out in 2011, second only to the US for operations. The most common procedures are liposuction and breast augmentation.
"When a woman goes for plastic surgery, it's 100 per cent competitive," said Dr Luiz Victor Carneiro, who has worked with Ivo Pitanguy, the world-renowned plastic surgeon who is based in Rio.
"Some come here and want unbelievable things and if I realise that is happening, I don't do the surgery.
"There is a great vanity here in Brazil, we expose too much of our body - especially in Rio."
Dr Barbara Machado, who has also worked with Dr Pitanguy, said that there was a spike in young women seeking surgery towards the end of every year, to be ready in time for the carnival.
Becoming a drum queen, even though it is usually unpaid, can lead not just to celebrity but also to sponsorship and marketing deals.
Rayssa Oliveira, 22, the drum queen for Beija-Flor samba school who will also be under the spotlight this weekend, has had liposuction and breast implants - and has no regrets.
"Everyone wants to be at the front of the percussion section," she said. "But I'm the queen. I represent a marvellous school and I'm very grateful. There are no words to describe how I will feel when carnival begins."
She said that she had the surgery for her own benefit. "I work for carnival all year. I travel outside the state, promoting the name of the Rio carnival."
Nor is spectators' appetite for the carnival likely to diminish. Last year it attracted 1.1?million visitors from outside Rio, of whom 350,000 were from abroad, generating an estimated pounds 465?million for the city. Millions more watched it on television.
And for all her criticism, even Ms Vieira remains a fan. "It's perfect," she said. "Not because of the money, but because it's about the Brazilians who play every instrument, the people who work from 7am to 7pm to make it happen.
"The whole Brazilian people are represented by what happens on the avenue. It's still the best spectacle in the world."