The Korean goalkeeper accepted his side's defeat against the CONCACAF champion in the Club World Cup quarterfinal and says Los Rayados could beat European champion Chelsea.
The match between the Asian Champions League winners and the CONCACAF Champions League winners was largely one-sided, and Kwang was accepting of the gulf in difference.
"I learned a lot about football from today's defeat, there are a lot of really good football players in the world," he said. "No. 9 (Aldo de Nigris) and No. 14 (Jesus Corona) played very well [for Monterrey]. They got speed and and their technique was even greater. Monterey plays very well, they might beat Chelsea.
"I can't say anything about my own performance today, I conceded three goals."
Ulsan goalscorer Lee Keun-Ho also chipped in with praise for the Mexican side, adding: "Monterrey is really good team, their pressing is great."
For Monterrey's De Nigris, the match was decided by the tactical decisions his team made.
"We focused on defending Kim Shin Wook, and we defended him as a team," De Nigris, Monterrey's vice captain, said. "We especially focused on limiting opportunities from set pieces, and we we got our play right. We didn't hurry even when we were put under pressure."
Monterrey will next face European champion Chelsea in a semifinal bout on Dec. 13.