Kiatisak Senamuang's stint as Port coach could end today when his men meet Chonburi in Thai League 1.
Kiatisak took charge at Port after he quit as coach of the national side a few months ago. But Port under "Zico" have had a poor run with one win, four defeats and three draws.
In their previous home match at PAT Stadium, Port took a 3-1 lead only for relegation contenders Sukhothai to stage a late comeback to earn a 3-3 draw.
In last week's game, Port lost 2-1 at Police Tero after conceding a last-gasp goal.
Upset by the poor results, a large number of Port fans have called for Kiatisak's head.
"We have made mistakes in several matches but the coach has to shoulder responsibility," Kiatisak told a press conference yesterday.
"I worked [as coach] at Chonburi in 2009 and know them quite well. I have prepared my tactics for this match. If we can't beat Chonburi, I will submit my resignation.
"I have talked to [Port chairperson] Nualphan [Lamsam] but I can't tell you the details of our discussion."
Meanwhile, Chonburi have problems of their own, as coach Therdsak Chaiman's tenure at Chonburi could also reach an end today.
The Sharks were seen as title contenders before the season but now lie in sixth.
Chonburi media manager Jeerask Chomthong said: "Therdsak's future will be determined by the executive committee. We have seven matches left in Thai League 1 and we are still in the League Cup. If we have good results in the remaining matches, then Therdsak should remain as coach."
There are two top-of-the table clashes tonight with leaders Buriram United hosting fourth-placed Bangkok Glass and second-ranked SCG Muang Thong United at home to third-placed Bangkok United.