Treble winners Buriram United have signed three players over the past few days.
Buriram chairman New Chidchob unveiled the club's latest signing, Serbian midfielder Goran Causic, on Monday.
Causic, who represented his country at the U19 and U21 levels, has played for Osasuna in Spain, Red Star Belgrade of Serbia and Arsenal Tula in the Russian Premier League.
Earlier, the Thunder Castle signed forwards Frank Castaneda of Colombia and Lonsana Doumbouya from Guinea.
Castaneda played for Moldova's Sheriff Tiraspol last season when they beat eventual winners Real Madrid in the group stage of the Champions League.
Doumbouya was the Thai League 1 top scorer in 2019 when he netted 20 goals for Trat.
Midfielder Goran Causic, right, poses with Buriram United chairman Newin Chidchob.
He has also played for Thai club Prachuap and Chinese team Shanghai Shenhua.
The new arrivals signal Buriram's intent of defending the Thai League 1, FA Cup and League Cup they won last season.
Buriram also want to do better in the AFC Champions League after failing to reach the group stage last season.
Buriram have lost forward Supachok Sarachart who has joined Japanese side Consadole Sappororo on a six-month loan deal.
Meanwhile, Japan will host this year's AFC Champions League knock-out stages for east Asian clubs, the Asian Football Confederation announced yesterday.
The East Zone's round of 16, quarter-final and semi-final matches will be played in August as single-leg ties, the AFC said.
Thailand's Pathum United will meet Hong Kong's Kitchee.