Engineers in Chile say they will attempt to drill a second tunnel in a bid to free 33 trapped miners sooner than the 120 days originally forecast.
The mining experts said Saturday the second rescue tunnel could be completed in two months under ideal conditions. The miners have been trapped since August 5.
Chilean officials say five of the miners, who were thought to be suffering from depression, have recovered.
Health Minister Jaime Manalich said the miners improved after receiving good food and news from their families.
On Friday, Manalich described the five men as isolated and not eating well. Manalich said a psychiatrist would attempt to treat the men over an intercom system lowered into the mine.
Excavation work to free the men is expected to begin soon.
The workers were trapped when part of the gold and copper mine collapsed on August 5. Rescuers first made contact with them on August 21.
Officials organizing the rescue effort say some of the miners will have to lose weight to fit through the rescue shaft.
Small-diameter holes have been drilled to communicate with the men and to deliver food and other supplies.
Chile has asked the U.S. space agency NASA and Chile's submarine fleet for advice on survival in extreme, confined conditions.
Some information for this report was provided by Reuters.