Engineers drilling to reach 33 trapped miners in Chile say they have just over 100 metres to go.
But the main drill has had to slow because it is passing close to a mine tunnel and there is a risk of collapse.
The miners have been trapped below since 5 August and engineers expect to reach to them in the next few days.
Rescuers and navy medics who will go down the shaft to help the miners out have begun rehearsing the operation.
The BBC reports rescuers had almost given up the search when they located the miners 17 days later.
They have been trapped underground longer than any previous group.