His Majesty the King's love for sports knows no bounds and it was his passionate involvement from the hospital bed that inspired the Thai national football team to regain Asean glory last year.
Thailand came from 3-0 behind to lose 3-2 in the second leg of the AFF Suzuki Cup final against Malaysia in Kuala Lumpur.
The result was enough for coach Kiatisak Senamuang's men to end a 12-year title drought in the biennial championship after a 2-0 home win in the first leg.
Prof Udom Kachintorn, dean of Siriraj Hospital's Faculty of Medicine, said the King, who was staying at the hospital at that time, watched both legs of the final on TV.
“In the first leg, the King woke up to watch the second half. His Majesty slept in the afternoon and woke up at 7pm [kick-off time] to watch the second leg,’’ the doctor said.
“When Thailand trailed 2-0 at half-time, the King asked his principal private secretary to phone Kasem Jariyawatwong, the team manager, to tell him that the King was watching the match and wanted to give them moral support.”
After Thailand won the title, the King smiled and said "brilliant", according to Udom.
His Majesty, who celebrates his birthday on Saturday, has also inspired and encouraged a large number of Thai athletes to victories.
It has become a tradition that Thai athletes will lift a portrait of the King after their success.
His Majesty loves sports and has been a patron of several sporting events and associations.
When he was younger he played several sports including badminton and tennis, and was Thailand's top sailor in the 1960s.
His Majesty is the first Thai monarch to have competed in an international sporting event when he took part in sailing at the Southeast Asian Peninsular (SEAP) Games, now the Southeast Asian (SEA) Games, in 1967.
The King won the gold in the OK dinghy class, the achievement being all the more remarkable as he had built his own boat. He claimed the title in Pattaya on Dec 16, which has since become Thailand's National Sports Day.
The International Olympic Committee (IOC) awarded him the Insignia of the Olympic Order in 1987 and presented him with the Lalounis Cup in 2001 for his leading role in supporting and promoting sports.
In 2012, the King received the President's Medal from the Badminton World Federation for his contribution to the sport.
“All sports must be played according to the rules,” the King once said.
On another occasion, he said: "Sports are important in the development of the country and people."
The King has always encouraged athletes to put the sporting spirit first, and strive for victory and friendship.