Chilean officials believe a drill carving an escape route for 33 trapped miners will reach them within the next 24 hours.
"Today could be a great day," Chilean Mining Minister Laurence Golborne said on Twitter Friday.
CTV's Lisa LaFlamme, reporting from the mine site in Chile, said officials are cautiously optimistic that the drill could reach the underground chamber where the miners are by late tonight.
"But they warned that this is the trickiest part of the entire operation, they had to change the drill bit on the hammer so it moves slower, because this is the area where a collapse is obviously an enormous risk," she told CTV News Channel by phone.
Still, officials say if all goes well, it could be Tuesday or Wednesday before the first miner makes it out. The men have been stuck underground since the Aug. 5 collapse.
The miners' families are keeping vigil while some 800 journalists have arrived on site, in what is expected to be a made-for-TV spectacle when the men are pulled out one-by-one.
The men will be pulled up through the escape route in a capsule, really little more than a small cage, named "Phoenix."
Doctors have put the men on a strict health regimen so they can fit in the Phoenix.
The miners have been divided into three groups, so that the strongest miners will be the first out because they will be best suited to operate the Phoenix if there are any problems, LaFlamme said.
Once the first of the three drills makes it to the underground refuge, a video camera will be lowered through the shaft to see if the miners can be pulled up through the exposed rock, or if the shaft must be encased with steel piping.
The casing would add an additional three to eight days to the rescue operation.
With files from The Associated Press
