Though the majority of the world's leagues are still in their off-season, in Mexico it is all systems go with the 2009 Apertura kicking off this Friday. And with a number of clubs bolstering their ranks in a bid to unseat champions UNAM Pumas, it promises to be another exciting and close-fought campaign.   

Three traditional Mexican powerhouses, America, Guadalajara and Cruz Azul, will be determined to bounce back after the disappointments of the Clausura, while the ever-ambitious Toluca and Pachuca once again find themselves among the pre-tournament favourites. takes a closer look at one of the world's most passionate leagues and assesses the teams' prospects for the season ahead.

Group 1: Two obvious candidates
In the first of the six-team sections, the two contenders that immediately stand out are Toluca and Guadalajara. Widely tipped again this year, Los Diablos will be hoping that the departure of Sergio Santana and Mario Mendez, coupled with that of star man Paulo Da Silva to English Premier League outfit Sunderland, can be quickly overcome. Chivas, for their part, have once again turned to their extraordinary youth academy for reinforcements and look to have a more mature squad than in the previous campaign.

Out to rain on their parade, however, will be Ricardo La Volpe's Atlas. The coach they call Bigotón has put his faith in many of the same players with whom he worked so successfully during his previous stint at the club earlier this decade. Three in particular that have Atlas fans looking to the future with optimism are Daniel Osorno, Miguel Zepeda and Mario Mendez, back wearing the Rojinegra jersey again after varying periods of time away from the club.

A glance at the remaining Group 1 sides raises more questions than answers. Will Indios of Ciudad Juarez be able to repeat the fairytale of last season, when they shocked almost everyone by reaching the Clausura semi-finals? Can San Luis regain their place at the country's top table after a championship-to-forget last time out? And will recently promoted Queretaro be able to maintain their top-flight status despite not significantly strengthening their squad?

Group 2: Battle of the big guns
Pachuca and America seem the obvious candidates to emerge from the second group. Los Tuzos, runners up in the recent Clausura, have added to their already impressive squad with the acquisition of Juan Carlos Cacho and Damian Manso, though they did lose their respected coach Enrique Meza. America, meanwhile, made perhaps the two biggest pre-season signings with the purchase of Colombian defender Aquivaldo Mosquera and Argentinian midfielder Daniel Gastón Montenegro, two quality additions that could finally bring some cheer to beleaguered Águilas supporters.

Perhaps the club best equipped to challenge the aforementioned duo are Monterrey, who have managed to keep intact the nucleus of their squad from the last campaign. Not quite at this level are the remaining trio of Morelia, Puebla and Jaguares, though all have plenty of potential and the capacity to feature should any of the favourites slip up.

Group 3: Champions and heavyweights
Naturally enough, the standout side in the final sextet are defending champions UNAM Pumas, although they can expect stiff competition from every quarter. Just like in the build-up to the previous campaign, Los Auriazules have opted not to enter the transfer market but instead to fill the few openings they have with the pick of their prolific youth academy. No one will be underestimating the talent at Ricardo Ferreti's disposal as he attempts to steer the club to both of this year's championships, a feat achieved only once before (by the Pumas themselves in 2004) since the opening/closing league format was introduced.

After a catastrophic showing in this years Clausura, in which they endured the humiliation of finishing last, Cruz Azul have left no stone unturned in their quest to restore the team to former glories. To this end, the club have brought in Enrique Meza, a coach of proven pedigree, and players of the stature of Emmanuel Villa, Jesus Corona and Melvin Brown. Two other clubs with enviable squads are Santos Laguna, who retain the side that performed so well in recent years, and Tigres who, after some sweeping changes, will first and foremost be looking to secure their place in the top flight.

The remaining two sides in the group will also fancy their chances. The team formerly known as Tecos may have changed their strip and now go by the name of Estudiantes, but they have an accomplished coach in Miguel Herrera and a very competitive squad. As of course do CONCACAF champions Atlante, who, as well as their league ambitions, will be keeping one eye on Abu Dhabi, where they will represent their region at the FIFA Club World Cup in December.