A major operation to rescue 10 workers trapped in a flooded coal mine in northern Mexico was approaching a crucial moment on Saturday, President Andres Manuel Lopez Obrador said.
"Today is a decisive day because, according to the experts, we'll know if it's possible for the divers to enter safely," he tweeted.
More than 300 soldiers and other personnel have joined the rescue effort in Coahuila state about 1,130 kilometers (700 miles) north of Mexico City, the government said.
Five workers managed to escape from the crudely constructed mine in the initial aftermath of the cave-in on Wednesday, but since then no survivors have been found.
The focus has been on pumping out water from the mine in Agujita in the municipality of Sabinas to make it safe enough to enter.
Authorities said that the three mine shafts descended 60 meters (200 feet) and on Friday the floodwater inside was reported to be 30 meters deep.
"The main problem is the flood, although the pumping equipment is sufficient," said Lopez Obrador.
Coahuila's state government said the miners had been carrying out excavation work when they hit an adjoining area full of water, causing the shaft to collapse and flood.
Family members spent a third night waiting anxiously for news after the latest disaster to strike Mexico's main coal-producing region.
"I feel desperate, not knowing what's happening and when I'll see him again," said Jesus Mireles Romo, whose father was among the missing.
"But I have faith that it will turn out well, that they will all get out," he told AFP, his eyes red from crying.
Coahuila has seen a series of fatal mining accidents over the years.
Last year, seven miners died when they were trapped in the region.
The worst accident was an explosion that claimed 65 lives at the Pasta de Conchos mine in 2006.
Only two bodies were retrieved after that tragedy and the families have repeatedly urged the authorities to recover the others.