Brazilian national soccer team player Ronaldinho gestures during a news conference at Wembley stadium in London February 5, 2013. Brazil are set to play England in an international friendly soccer match on Wednesday.??[Photo/Agencies]

RIO DE JANEIRO - Brazilian rivals Atletico Mineiro and Sao Paulo are expected to provide the highlight of the opening week of this year's Copa Libertadores group stage when they clash at Atletico's Estadio Independencia in Belo Horizonte on Wednesday.

Both clubs are laden with star quality and considered by most pundits as leading contenders to win South America's most prized club trophy in 2013.

While Sao Paulo have lost 20-year-old winger Lucas Moura to Paris-Saint Germain since winning last year's Copa Sudamericana, they have been bolstered by the additions of 2002 World Cup-winning centre-back Lucio and former Santos playmaker Paulo Henrique Ganso.

Their squad also boasts prolific striker Luis Fabiano and ageless goalkeeper Rogerio Ceni, who at 40 is still the team's designated free-kick and penalty taker.

They face an Atletico Mineiro outfit which has arguably been even busier in the off-season transfer market.

Among the new arrivals are one-time Brazil striker Diego Tardelli from Qatar's Al-Gharafa as well as former Arsenal midfielder Gilberto Silva.

The duo adds class to a squad already comprising two-time FIFA world player of the year Ronaldinho and emerging midfield starlet Bernard.

Tardelli, who has returned for a second stint with the side he represented from 2009 to 2011, is confident of developing a quick on-field rapport with Ronaldinho, despite having only arrived at the club last week.

"It's an honour to be playing with Ronaldinho, I'm a fan and have always followed him closely," the 27-year-old said.

"Now I'm playing alongside him. I hope we can build up a good understanding on the pitch. I don't believe it will be difficult because he is intelligent and I also know how to think on the pitch."

Among other opening-week fixtures, reigning Argentine champions Velez Sarsfield are away to Ecuador's Emelec on Tuesday, Boca Juniors host Mexico's Toluca on Wednesday while Brazil's Gremio, coached by former Real Madrid boss Vanderlei Luxemburgo, are at home to Chile's Huachipato on Thursday.