ATHENS - Greece, beset by economic difficulties and a migration crisis, will hold a traditional ceremony Thursday for the Rio Olympics as Brazil battles its own political woes.

The dress rehearsal for the lighting of the Olympic flame in ancient Olympia went ahead smoothly Wednesday, and the official ceremony on Thursday will launch a four-month torch relay culminating at Maracana Stadium for the Games opening ceremony on August 5.

The torch harks back to the ancient Olympics, when a sacred flame burned throughout the Games. The tradition was revived in 1936 for the Berlin Olympics. The Olympic torch relay will run through part of Greece before being handed over to Brazilian officials on April 27 for the start of a 95-day relay across the South American country a week later.

A highlight of the Greek leg will be the passing of the torch on April 26 through the refugee camp of Eleonas, where one of the hundreds of refugees housed there will carry the flame. The runner's name is to be announced on Friday, Greek organisers said.

The International Olympic Committee has given the green light for a team of up to 10 refugees to take part at the Rio Olympics. So far, 43 high-performance athletes, who are also refugees, have been identified as possibly being eligible for the Games in Brazil.

Bach said the final number would depend on meeting qualifying criteria, adding that the team would compete under the flag of the IOC. "We have all been touched by the magnitude of this refugee crisis. By welcoming this team, we want to send a message of hope to all the refugees in the world," Bach, who visited Eleonas in January, said in March.

While Greek President Prokopis Pavlopoulos will be attending Thursday's official ceremony, his Brazilian counterpart Dilma Rousseff has cancelled her planned attendance as she is currently fighting for her political life amid a deep recession, impeachment proceedings, mass protests and a corruption scandal.

Brazil will be represented at Olympia by the president of the Rio 2016 organising committee, Carlos Nuzman, and sports minister Ricardo Leyser. Actress Katerina Lehou, playing a high priestess, will light the flame on Thursday using the rays of the sun reflected off a concave mirror.

After giving thanks to the ancient Greek sun god Apollo, Lehou will light the Rio Olympic torch held by the first relay runner, artistic gymnast Lefteris Petrounias, Greece's reigning world champion on the still rings.

Petrounias will pass it on to Brazilian volleyball legend Giovane Gavio, an Olympic gold champion at the 1992 Barcelona and 2004 Athens Games who is now director of volleyball for Rio 2016. Gavio had also carried the torch in Rio de Janeiro during the relay for the Athens 2004 Games. The Olympic torch will be handed over to Nuzman in the presence of Pavlopoulos, Bach and Greek Olympic Committee president Spyros Capralos on April 27 in a ceremony at the historic all-marble Olympic stadium in Athens, site of the first modern Games in 1896.

Preparations in Rio have been overshadowed by a government crisis, with Rousseff facing impeachment after being accused of juggling government accounts to disguise budget shortfalls during her 2014 reelection.

However, Rousseff insisted Tuesday that preparations for the 2016 Olympic Games in Rio de Janeiro are ahead of schedule. "The Games are in a totally adequate situation, we're even a little ahead of schedule and more so than we had planned for," Rousseff told a press conference in Brasilia.