In this photo, Vietnam head coach Park Hang-seo awaits the start of the second leg of the ASEAN Football Federation Championship final against Thailand at Thammasat Stadium in Pathum Thani, Thailand, on Monday. (Reuters)

It was a bitter ending of an otherwise successful run for South Korean football coach Park Hang-seo, as his Vietnamese team bowed out to Thailand with a regional title on the line Monday night.

Thailand successfully defended their ASEAN Football Federation Championship title with a 1-0 victory over Vietnam in the second leg of the final, prevailing on a 3-2 aggregate. Thai captain Theerathon Bunmathan scored the lone goal in the match at Thammasat Stadium in Pathum Thani, Thailand.

This was Park's final tournament with Vietnam, a team that he began coaching in October 2017. Over Park's five-plus years in charge, Vietnam enjoyed unprecedented success at both under-23 and senior levels.

Vietnam won the 2018 AFF title, their first in 10 years, and reached the quarterfinals at the 2019 Asian Football Confederation Asian Cup, matching their best performance at the top continental tournament.

Vietnam also reached the final Asian qualification round for the 2022 FIFA World Cup.

Park guided the U-23 national team to gold medals at the 2019 and 2021 Southeast Asian Games after taking them to second place at the 2018 AFC U-23 Asian Cup and fourth place at the 2018 Asian Games.

Vietnam broke into the top 100 in the FIFA rankings on Park's watch and they're currently 96th.

Park was an assistant coach for South Korea under Guus Hiddink when the Dutch tactician led the upstart team to the semifinals at the 2002 FIFA World Cup. But Park hadn't enjoyed much success for himself as a head coach until finding a new home in Vietnam.

In October last year, the Vietnam Football Federation announced it had reached "a mutual agreement" with Park to end their journey after the end of Park's current deal on Jan. 31, 2023. And the AFF Championship was to be Park's final competition with the team.

Following Monday's loss, Park, 64, thanked his players for their effort and apologized to Vietnam fans for not delivering them a trophy.

"This result was due to my shortcomings as head coach," Park said. "The players did their best today and I am grateful for that. I hope people will encourage these players so they can continue to grow, rather than criticize them."

Park said he would miss Vietnamese players and he would continue to root for them.

"It breaks my heart that I will no longer be with the players I love so much," Park said. "I will never forget all the memories I've made with them. I will now become a fan of Vietnamese football."

Park also said he hadn't given much thought to his immediate future beyond Vietnam.

"When I am doing something, I don't really think of anything else," Park said. "The tournament just ended, and my contract runs through Jan. 31. I will meet with my family and my agent afterward to talk about my future. Football is the only thing I am good at, and I will try to make the best choice for myself to stay in football." (Yonhap)