Tournaments are like birthdays: they are as significant as you want them to be. To many the Confederations Cup is a meaningless intrusion on the football calendar, a rinky-dink competition that proves nothing more than Fifa's greed. After all, the World Cup already exists to establish the best team on the planet so what, other than money and attention-seeking, is the point of a mini-tournament between the leading teams from each continent?

It is not just countries who have no hope of ever qualifying for it that are sniffy about it: Germany have twice declined to take part, as did France's 1998 world champions. But this year's edition promises to be different because, perhaps for the first time, all of the participants are taking it seriously, meaning we could witness exciting contests and gain valuable insights into how some of the best teams from around the globe are shaping up before the main event, next summer's World Cup.

Each of the eight competing nations have their own reasons for wanting to do well in the tournament that kicks off on Saturday with an opening match between the only two countries already guaranteed to be at next year's showpiece: the hosts, Brazil, and the Asian champions, Japan, who last week became the first team to reach the World Cup through the qualifiers.

Italy, who complete Group A with Mexico, arrive eager not to make the same mistake as in 2009 when, rather than use the tournament as an opportunity to build, they treated it like a post-season jolly and wound up losing to Brazil and Egypt, a performance that set the tone for their display at the 2010 World Cup, where they were eliminated in the group stages without winning a game.

"Four years ago in South Africa we didn't approach [the Confederations Cup] properly and we paid the price," said the Italy defender Giorgio Chiellini. "Being together for a month provides a great chance to improve – we know that now."

Italy's attempts to improve will make them one of the most interesting sides to watch over the next fortnight. Cesare Prandelli may have guided the team to the Euro 2012 final during his first tournament in charge but his renovation of the side is far from complete. The manager is still searching for the right blend and identity for the Azzurri. He has generally made Italy faster and more enterprising since taking over two years ago but, with qualification for the World Cup within his grasp, he tried a new formation and more cautious approach away to the Czech Republic this month and was lucky to escape with a 0-0 draw.

The squad he has taken to Brazil shows that he feels the need to continue experimenting, as, alongside stalwarts such as the 34-year-old Andrea Pirlo (whose natural heir, Marco Verratti, is furthering his development at the European Under-21 Championship), there are several relatively inexperienced internationals. Against Mexico Prandelli is considering placing greater emphasis on wing play, with Torino's Alessio Cerci and Lazio's Antonio Candreva possibly being introduced in a bid to ensure better supply to Mario Balotelli and Stephan El Shaarawy, the blossoming young strikeforce on which Italy are banking. Prandelli's proven open-mindedness means all the players who have travelled to Brazil will believe they have a chance of establishing themselves in his plans if they perform well.

One traditional explanation for Mexico's failure to go far in World Cups is the weakness of their qualification route, which leaves them unaccustomed to facing top-class opponents. That is why they relish the Confederations Cup and more than 110,000 fans turned up to the Estadio Azteca to watch them beat Brazil in the final of the 1999 edition.

That theory does not stand up so well at the moment, as Mexico are struggling to make it to next year's World Cup, lying third in the Concacaf qualification table because of their inability to score regularly. Their manager, José Manuel De La Torre, is still trying to find a formula for alleviating the dependency on Manchester United's Javier Hernández and that task is complicated by the absence through injury of Oribe Peralta, who excelled when Mexico won gold at the London Olympics. However, many of the other members of that thrilling squad are included for this tournament.

The South American champions, Uruguay, are also placed precariously in their World Cup qualification group and seeking a formula that does not rely so much on Luis Suárez or, more precisely, gets the best out of both Suárez and Edinson Cavani so that both of the country's world-class strikers can fire together. Cavani has seldom been as deadly for his country as he is for Napoli, partially because he seldom plays in the same position.

He kept Uruguay's qualification hopes alive by scoring the winning goal against Venezuela this week but Suárez was suspended for that and is back for the Confederations Cup, giving the manager, Oscar Tabárez, further scope to find the right way of accommodating the potentially fearsome pair, as well as Diego Forlán and Southampton's Gaston Ramírez.

In addition to its value in terms of preparing for the World Cup, the Confederations Cup is significant in its own right to Uruguay for the same reason that it is important to their first opponents, Spain. Both countries want to win it to complete their collection of international trophies.

Tahiti will be highly motivated too, knowing they will probably never feature so prominently on the international stage again, though it is doubtful that the Oceania champions' enthusiasm will suffice to make them competitive. Their first opponents, Nigeria, should have far too much quality for them although it is difficult to know exactly what to expect from Stephen Keshi's young side, who have stuttered since winning the Africa Cup of Nations earlier this year and had their departure for Brazil delayed by a dispute over unpaid bonuses.

The favourites are, of course, the home side. After drawing with England earlier this month, Brazil beat France 3-0 but now, at last, they get to play competitive matches. That is vital for a manager, Luiz Felipe Scolari, whose methods remain the subject of intense debate, and a squad that features just four players with World Cup experience. Win and they will placate their compatriots, at least for a while. Lose and the pressure could trigger irresistible demands for change before the World Cup.