Spanish and European champions Barcelona began their pre-season training on Monday with just their Argentinian and Brazilian players who took part in the Copa America missing. Andres Iniesta, Xavi, Carles Puyol and Gerard Pique were among the 18 Barca players who took part in a light training session after completing physical tests. Puyol, who underwent an operation in June on his left knee to remove loose cartilage, will work on building up muscle strength this week, the club said in a statement. "The injury is healing well and within the predicted time schedule," it said. Barca's Argentine players Lionel Messi and his team-mates Gabriel Milito and Javier Mascherano along with the club's Brazilian players Daniel Alves and Adriano have been given extended leave to take part in the Copa America. The tournament final is on July 24, but Argentina lost their quarter-final against Uruguay on Saturday and Brazil went out at the same stage to Paraguay on Sunday