Coach Lee Jang-soo believes Beijing Guoan face a stiff test from Ulsan Hyundai in the Asian Champions League tonight.

The Korean coach thinks it is his Chinese sides toughest test to date despite sitting equal top of their group with a win and a draw from two matches.

What makes it tougher for Jang-soo is that he is returning home to face a team coached by his old university friend Kim Ho-kon.

"Any time that I return to coach a game in my home country against a man that I know well, it is a very emotional time for me," said Jang-soo.

"Preparing for an away match like this is always difficult.

"This is my team's first real test of the season playing away against a difficult opponent with a lot at stake. However, I feel my team is fully prepared."