Lee Yong said Yun, the Olympic host country's only gold medal hope in the men's skeleton, is "perfectly" ready for the Games.
"He has no reason to think about others," Lee told Reuters in a phone interview after hours of meetings to discuss Yun's tactics for Thursday.
"He will have to run his four races with same records and do his own race, if so, he can win his gold medal and we are all set."
Yun, who made history last month by becoming the first Korean world champion in men's skeleton, did not take part in the final round of the season in Germany in order to practise for the Olympics.
Lee said Yun had been training on home ice for about two years and knows the curves and turns of the Olympic Sliding Centre better than anyone.
"At first, we were a bit confused but now we know the track well and have practised runs almost perfectly," the coach said.
"People often think that home advantage is simply having more opportunities than others, but actually it is more about making no mistakes to improve records."
Yun practised twice on Tuesday at the Olympic Sliding Center in Pyeongchang and ranked second in each training run, but he did not show up for official training heats on Wednesday.
Yun will make his first two runs on Thursday and the final two on Friday when the medallists will be decided.
"I'm sure he'll run his best race tomorrow. Today he had a good rest," the 40-year-old Lee said.
(Reporting by Jane Chung, Additional reporting by Ian Ransom, editing by Ed Osmond)
