Muang Thong United knocked out defending FA Cup champions Bangkok United 2-1 to book their berth in the quarter-finals of the competition on Wednesday night.
All the goals came in extra-time, with Poramet Arjvilai scoring the winner two minutes from time to send the Kirins into the last eight.
Teerapat Nantakowat had put the Kirins ahead in the 96th minute before Rungrat Poomchanthuek equalised for the Angels seven minutes later.
Meanwhile, an extra-time penalty from Goran Causic sent Buriram United into the last eight as the Thunder Castle rallied to defeat Chiang Rai United 2-1.
Jordan Emaviwe gave the Beetles the lead in the 17th minute before Dion Cools made it 1-1 in the 42nd minute.
During extra-time, Chiang Rai defender Sanukran Thinjom fouled Suphanat Mueanta in the penalty area and Causic put away the decisive spot kick to send hosts Buriram through.
In other last-16 matches, Chanthaburi defeated Rajpracha 2-1, Phrae United beat Nakhon Si United 2-1, Khon Kaen lost to Sukhothai 0-1, Samut Sakhon City were trounced 4-1 by Nakhon Ratchasima, BG Pathum United routed Surin City 4-1 and Ratchaburi hammered Suphanburi 7-1.
Jadet quits as U17 coach
Jadet Meelarp has stepped down as coach of the U17 squad after his team lost to China 2-0 in their final AFC U17 Asian Cup Group A match in Saudi Arabia on Wednesday night.
The defeat meant Thailand finish the group stage in last place after three defeats in as many matches.
Thailand had earlier lost 4-1 and 3-1 to Uzbekistan and Saudi Arabia respectively.
"I would like to apologise to the Football Association of Thailand and the fans for the bad results," said Jadet. "I have decided to end my role as head coach of the team so that the FAT can find a suitable person for this duty."
Hosts Saudi Arabia lost 3-0 to Uzbekistan in the other group match, but both teams have qualified for the quarter-finals of the competition.