The match is scheduled at Hua Mark Indoor Stadium at 7pm, while Ukraine take on Costa Rica in the other final Group A game at Korat Chatchai Hall at the same time.
Ukraine lead the group with four points, followed by Costa Rica and Thailand, who each have three points _ the Concacaf champions are ahead thanks to their superior goal difference. Paraguay are bottom of the group with just one point.
The top two teams from each of the six groups and four best third-placed sides qualify for the knockout stages.
With so much at stake, Thailand's clash with Paraguay promises to be a truly tense affair. The Thais are in a better situation as they could still progress to the knockout stages with a draw _ or even a defeat _ depending on the results of other matches.
Seen by many pundits as a dark horse to win the tournament, the Paraguayans, who were the only side to beat Brazil in South America's qualifying round, have no option but to win tonight.
The return of striker Emmanuel Ayala from suspension will surely help them in their bid to do just that. He will team up with his twin brother Gabriel.
The Thais have more room for error but will not want to rely on the results of other games.
Thailand are pinning their hopes on the fitness of their star man, Suphawut Thueanklang, who is nursing a groin injury.
Thailand coach Victor Hermans said: ''We have to win to make sure that we will advance. But it will not be easy because Paraguay are strong. We must not make mistakes. At least we must avoid defeat. A draw and we will have four points and that should be enough for us to reach the second round.
''Suphawut's injury is not very serious. We hope he will recover in time. If he fails, then we still have Apiwat [Chaemcharoen] to be replace him.''
Thailand will be without Kritsada Wongkaeo who is suspended and will be replaced by Konghla Lakka.
First-choice goalkeeper Prakit Dankhunthod should be available for selection after missing the Ukraine match through injury.
Thailand's deputy team manager Sutthiphan Wannawinwet said: ''We must stay focused in defence. Paraguay are strong but our players have condifence. I believe we will beat them.''
Tickets for Thailand's match against Paraguay have been sold out and the organisers will set up giant monitors to show live the game at the fan zone at Nimibutr Gymnasium.
P W D L GF GA Pts
Ukraine 2 1 1 0 8 6 4
Costa Rica 2 1 0 1 7 6 3
Thailand 2 1 0 1 6 6 3
Paraguay 2 0 1 1 6 9 1