Bangkok United edged BG Pathum United 1-0 in Thai League 1 on Sunday night to keep alive their slim hopes of winning the title.
On the other hand, the home loss saw BG coach Matthew Smith moved upstairs and replaced by Supachai Komsilp.
Thailand defender Manuel Tom Bihr scored the winner for the capital side after four minutes.
The Angels have 52 points, 12 behind leaders Buriram United, with six games remaining.
Bangkok United will host Buriram on April 4 after the international break. The Thunder Castle will retain the trophy if they defeat the Angels at True Stadium.
"We did not play well but it's good to get three points," said Bangkok United coach Totchtawan Sripan.
"It will be difficult against Buriram but we will fight for a win."
Although Pathum are ninth on 29 points, they are just seven points above the relegation zone.
However, the Rabbits can still finish the season with silverware as they are in the semi-finals of the League Cup.
Australian Smith has been appointed as technical director while his assistant Supachai has been named as interim coach.
"Our players have tried to do their best for our fans but the results have not been good," said Supachai, a former BG player.
"Sometimes, we concede easy goals, and it is difficult for us to score."
In another game on Sunday, Port defeated Sukhothai 2-0 at PAT Stadium thanks to goals from Airton Tirabassi in the 45th minute and Teerasak Poeiphimai in the 80th minute.
The league is taking a break for international matches and will resume on April 2.
Thailand players reported to the training camp on Monday ahead of two warm-up games in the UAE.
Among them are Japan-based duo Chanathip Songkrasin and Supachok Sarachart, and Supachai Chaided.
Forward Ekanit Panya has pulled out of the squad due to injury.
The War Elephants meet Syria in Dubai on March 25 and face the UAE in Abu Dhabi on March 28.