Both teams, who have already qualified for the quarter-finals, delivered an abject performance that saw all four players miss routine shots throughout.
Fans booed as shuttle-cocks were hit long or dumped into the net, prompting the referee to come on court twice to speak to the players before South Korea eventually won 21-14 21-11.
The result means China's world champion duo will only meet the country's number two pair if both teams reach the final. The Koreans may now have to get past the Chinese number two team to reach the final.
"Actually these opponents really were strong. This is the first time we've played them and tomorrow it's the knockout rounds, so we've already qualified and we wanted to have more energy for the knockout rounds," said Yu.
"Really, it's not necessary to go out hard again when the knockout rounds are tomorrow."
The South Korean players declined to comment.
- Sports & Recreation
- Yu Yang