Ulsan Hyundai goalkeeper Kim Young-Kwang says that Monterrey could upset Chelsea in the Club World Cup semi-final after the Mexican side beat his team 3-1.
The Japanese outfit were lacklustre in defeat in Sunday's quarter-final and the keeper accepted the gulf in class between the two clubs.
"I learned a lot about football from today's defeat; there are a lot of really good football players in the world," Kim told reporters after the match.
"No.9 [Aldo de Nigris] and No.14 [Jesus Manuel Corona] played very well [for Monterrey], they had speed and and their technique was even greater.
"Monterrey play 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 are a really good team, their pressing is great."
For De Nigris, the match was decided by the tactical decisions that his team made.
"We focused on defending Kim Shin-Wook and we defended him as a team," said the Monterrey vice-captain. "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."
The Mexican team will take on Chelsea on December 13 for a place in the final.