Engineers in Chile have begun drilling the rescue shaft through which they hope to eventually free the 33 men trapped in a collapsed gold mine.
The miners have been stuck 700m (2,300ft) underground for the past three weeks.
Officials say it could take up to four months for the tunnel to be completed and the men to be winched out.
Some of the miners have developed fungal infections and body sores in the hot conditions underground.
A huge Australian-made "Strata 950" excavator began work late on Monday.
The machine dug a narrow test hole, which will gradually be deepened and expanded to a width of about 60cm.
The miners will have to clear thousands of tonnes of falling debris in round-the-clock shifts, although officials say the men are in no danger of being hit.
The rescue shaft is likely to take 90 to 120 days to complete. Then a capsule can be lowered down to retrieve the miners one by one.
Mining Minister Laurence Golborne had said up to 10 options were being considered in the efforts to rescue the men.
But he dismissed suggestions that the men could be out within a month, saying: "Up to now there is no alternative... that would allow us to get them out in 30 days."
At present, rescue workers are using three narrow shafts to send essential supplies to the trapped men, and ensure they have adequate ventilation.
