Bottom club Rayong must avoid defeat against PT Prachuap in Thai League 1 on Tuesday to delay their relegation.
However, it is just a matter of time before their quick return to Thai League 2 is confirmed as they are 13 points from safety with five games remaining.
Prachuap, who are five points above the red zone, still need points to survive.
The Killer Wasps collected crucial points at the weekend when they beat Nakhon Ratchasima with Willen Mota on target.
The Brazilian forward has scored 13 league goals this season.
Prachuap coach Thawatchai Dumrong-ongtrakul said on Monday his players had more confidence after their win against the Swat Cats.
He hailed Willen as a key player in the team's fight against relegation.
"Willen has helped the team a lot. He has scored many goals and is currently our top scorer," Thawatchai said.
But Prachuap will be without Willian Henrique, another Brazilian forward, who is nursing an injury, the coach said.
He warned his men against complacency as Rayong players are strong physically.
In today's other match, Muang Thong United continue their chase for a top-three spot for a place in the 2022 AFC Champions League play-offs.
Fourth-placed Muang Thong are seven points behind Buriram United and Port, who share second spot with 48 points each.
Muang Thong received a boost at the weekend when they came from behind twice to draw 2-2 with bitter rivals Buriram.
Buriram visit relegation contenders Sukhothai, while Port are at lowly Suphanburi on Wednesday.
On Thursday, BG Pathum United, who have already secured the title, travel to Chonburi. The Rabbits are trying to become the third team to win the title with an unbeaten record after Buriram and Muang Thong.