Ulsan Hyundai hammered Thai League 1 side BG Pathum United 3-1 in their opening Group I game of the AFC Champions League in South Korea on Tuesday.
Martin Adam scored a hat-trick for the Korean champions.
The Hungarian forward opened the scoring in the 28th minute only for Singapore's Ryhan Stewart to equalise for the visitors after 41 minutes for a 1-1 tie at half-time.
Adam was on target again after 73 and 78 minutes as the two-time Asian champions ran out winners.
BG, led by Thailand international Sarach Yooyen and Teerasil Dangda, reached the quarter-finals last season.
In the other Group I match, Malaysia's Johor Darul Ta'zim were playing Japan's Kawasaki Frontale last night.
In Group F, Thai League 1 side Bangkok United face Lion City Sailors in Singapore at 7pm, Thai time, today.
The Sailors, coached by Aleksandar Rankovic, are back again after debuting in 2022.
It will be the Thai club's first ACL appearance as Bangkok United finished second in the 2022/23 Thai League 1 season.
However, they played in the competition once when they were known as Bangkok University in 2007.
"This is a historic match for us as it is Bangkok United's first in the AFC Champions League," Bangkok United coach Totchtawan Sripan said at a press conference on Tuesday.
"We are ready for the match and we have studied our opponents already. They have several good players."
He said the artificial turf at Jalan Besar Stadium should not be a problem for his players.
In the other Group F match, two-time champions Jeonbuk Hyundai Motors of South Korea host Kitchee from Hong Kong.
In Group H, Thai champions Buriram United take on China's Zhejiang, formerly Hangzhou Greentown, at 5pm.
Buriram are set for their eighth involvement and their first since 2019.
Two round of 16 finishes remain the Thunder Castle's best achievements in the ACL.
"We are very excited to be back to play in the AFC Champions League once again," Buriram coach Arthur Papas told a press conference on Tuesday.
"Every player in the team is looking forward to this important tournament. We have a high chance of winning the game as we will play at our home."
In the other Group H game, Melbourne City of Australia are at home to Japanese club Ventforet Kofu.
Meanwhile, Buriram have terminated their contact with coach Masatada Ishii.
The Japanese has been sent by club president Newin Chidchob to help national team coach Mano Polking as the War Elephants' technical chairman.
"Thank you everyone for supporting me all the time," he said in a social media post.