"Today is D-day for the extraction, with the boys at their best mental and physical conditions and medical teams as well as rescue teams ready for operation", said the governor.
Extracting everyone could take four days, but Sunday's success raised hopes that it could be done.
Thai officials said Saturday they are anxious that heavy monsoon rain could soon make the job even more hard and they may need to quickly rescue the boys and the soccer coach from a partially flooded cave by helping them make risky dives to safety.
Narongsak, who is heading the operation, said earlier Sunday that 13 foreign and five Thai divers were taking part in the rescue, and two divers were to accompany each of the boys, all of whom have been learning to dive only since Monday, when the first searchers found them.
Air tanks were planted along the route earlier on Monday. Eight of the boys, and their adult coach, remained inside after the divers exhausted their supplies of air.
As of Sunday, four boys were confirmed rescued from the cave, before the mission was paused, according to the BBC.
But the head of the mission, Narongsak Osottanakorn, yesterday suggested they would try in the coming days, even though the boys were weak and had no previous diving experience.
The members of the soccer team have been trapped by flooded waters inside the cave in Chiang Rai province in northern Thailand for two weeks.
He said that reunion would be delayed by 24 hours because of the need to perform exhaustive health checks and that after that, if all the tests were negative, then family could visit.
The boys urged relatives "not to worry" and asked for their favourite food once they were safely evacuated, in notes handed to divers.
"Football's Coming Home. First Wild Boars Out", a headline on one online Thai paper said on Monday, referring to a song chanted by English soccer fans at the World Cup now underway in Russian Federation.
Residents of the nearby town of Mae Sai, located directly on the border with Myanmar around seven miles away from the cave entrance, have been following the saga of the boys' disappearance and rescue efforts intently.
NowMedia will update this story as more information becomes available.
The boys who have already been rescued have been rushed to hospital for 48 hour observation following their ordeal. Officials are now limiting the number of rescue workers who can travel into the cave to reduce the amount of carbon dioxide that builds when they exhale.
Rescuers woke to gloomy skies and potential thunderstorms following a night of heavy monsoonal rains lashing the mountainous region.
The boys and their coach had been stranded in Tham Luang Nang Non when they went exploring in the cave after a scrimmage.
The search and rescue operation has involved dozens of global experts and rescuers, including a USA military team. On Sunday, he tweeted videos showing the submarine being submerged in the Palisades Charter High School swimming pool in Los Angeles.
The first boy made it out at 5.31pm (11.31am United Kingdom time), and at 7.47pm (1.47pm) the Thai navy SEALS announced: 'Fourth Wild Boar out of the cave!' The youngsters were assessed by medics at the cave entrance before being taken to hospital. "I want to say thanks for all the support, and I want to apologize".
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