With Tottenham Hotspur star Son Heung-min watching from the bench, Shanghai Shenhua striker Kim Shin-wook scored twice in the Group H romp in Goyang, two days after Yoo’s death was announced.
Former midfielder Yoo, who was 49 and had been battling pancreatic cancer, was a mainstay of South Korea’s memorable run to the 2002 World Cup semi-finals on home soil.
A moment’s silence and video tribute preceded the game, while the Korean team wore black armbands. After opening the scoring in the 14th minute, Kim and his teammates held up a South Korea shirt bearing Yoo’s name and his number, six.
Lee Dong-gyeong then swept home his first international goal before Kim’s penalty made it 3-0 against outclassed Sri Lanka, who at 204th are just six spots off the bottom of the world rankings.
Hwang Hee-chan rifled in the fourth before debutant Jeong Sang-bin, 19, joined Lee with his maiden international goal. Sri Lanka went down to 10 men when Asikur Rahuman was sent off in the 56th minute.
The result put South Korea, who are hosting Group H, three points clear at the top thanks to Lebanon’s late collapse against Turkmenistan.
The Lebanese were 2-1 up with five minutes left but Annaguliyev Guychmyrat equalised before Altymyrat Annadurdiyev grabbed the winner in the first added minute.