Brazilian coach Alexandre Gama bade farewell to Buriram United with a 1-0 win at Chiang Rai United in Thai League 1 late on Sunday night.
The victory, coupled with True Bangkok United's 2-0 shock loss at lowly Suphanburi, sent the Thunder Castle to the top of the table, ahead of the capital side on goal difference.
Supachai Chaided scored the winner for Buriram after 51 minutes.
"I'd like to thank Buriram for giving me the chance to coach the team for a second time," said Brazilian Gama who returned to Buriram last year.
"The players and I worked very hard to return to the top spot and we have done it."
Japanese coach Masatada Ishii, who has reportedly quit Thai League 1 side Samut Prakan, is tipped to replace Gama at Buriram.
Gama admitted that he was surprised that he had to leave Buriram when they are at the top of the table at the end of the first half of the season.
He said he would return to Brazil to meet his daughter who he has not seen for two years.
The 53-year-old coach said he was ready to work again in Thailand.
"I am ready to consider offers from other Thai clubs," he said.
Gama is one of the most successful foreign coaches in Thailand.
During his first spell with Buriram, he guided them to two league, one FA Cup and one League Cup titles.
He also steered Chiang Rai United to win the FA Cup in 2017 and 2018 and League Cup in 2018.
He has also managed Muang Thong United with little success.
"That was my worst spell in Thailand when Muang Thong finished fifth [in the league]," Gama said.
Meanwhile, relegation contenders Suphanburi stunned Bangkok United 2-0 in another game on Sunday.
Danillo Alves scored twice after six and 51 minutes.
Thai League 1 is taking a break to let the national team to compete in the Dec 5-Jan 1 AFF Suzuki Cup in Singapore.
The league will resume in January.