SCG Muang Thong United last night left for their AFC Champions League play-off with Shanghai SIPG without prolific striker Teerasil Dangda.
Coach Tottawan Sripan confirmed before leaving that Teerasil has been ruled out of tomorrow's third-round play-off because of a back injury.
"Teerasil is not travelling with the team to Shanghai because we want him to be fit for the King's Trophy match against Buriram United on Feb 20," said Tottawan.
Muang Thong, the Thai Premier League runners-up, won against Malaysia's Johor Darul Ta'zim 3-0 in a penalty shoot-out after a scoreless draw in their second-round play-off match at SCG Stadium on Tuesday night.
The winners of tomorrow's game will qualify for the group stage, joining Melbourne Victory, Suwon Samsung and Gamba Osaka in Group G of the AFC Champions League.
Chonburi, who edged Myanmar's Yangon United 3-2 after extra-time last Tuesday, also left for Japan yesterday for their third-round play-off match with FC Tokyo tomorrow.
The winners of the clash between Chonburi and FC Tokyo will qualify for Group E, which includes Jeonbuk Hyundai Motors, Jiengsu FC and Becamex Binh Duong.
The Sharks' coach Therdsak Chaiman said: "FC Tokyo are a very good side and they have many national team players. We have been preparing hard and will be trying our best but the cold weather in Japan can make things difficult for us."