Thailand interim coach Sirisak Yodyardthai said his players lost concentration that allowed China to seal a 2-1 comeback win in the Asian Cup last 16 round in the United Arab Emirates on Sunday.
At Al Ain's Hazza bin Zayed Stadium, young forward Supachai Chaided gave Thailand the lead after 31 minutes only for Marcello Lippi's men to score twice in a four-minute span in the second half.
A close range strike by Xiao Zhi in the 67th minute and Gao Lin's penalty after 71 minutes sent China to the quarter-finals where they will face Iran who beat Oman 2-0.
"Our players lost concentration. It's a pity we couldn't keep the score line we had at 1-0," said Sirisak.
"I'm very proud of the players and the performance they put in today. Both teams executed well and congratulations to the China team.
"We were hurt by the direct football that China played and that caused errors in our defence. In the last 10 or 15 minutes, we were back in the game but that was too late.
"We were quite confident of keeping the lead but that didn't happen and hats off to China for adjusting their tactics and coming back into the game by scoring two goals."
Sirisak was appointed caretaker coach after Milovan Rajevac was sacked following the War Elephants' 4-1 loss to India in their opening group game.
Under Sirisak, Thailand beat Bahrain and drew with the UAE to earn a place in the knockout stages.
"Regarding my future, it depends on the Football Association of Thailand to make a decision when we return home," said the 49-year-old coach.
Meanwhile, Thailand captain Teerasil Dangda said he wanted to continue playing for the national team.
The 30-year-old striker is the only player from the Thai team that played in their previous Asian Cup in 2007.
He said he initially thought UAE 2019 would be his last tournament with the national side but has since changed his mind.
"It's a pity that we lost but I am not sad. We fought hard and gave our all,'' said the SCG Muang Thong United striker.
"If they still want me, I will continue playing [for the national team]. But I have to work hard and look after myself.
"I hope Thailand will qualify for the Asian Cup again and come back with a stronger team."
Teerasil, arguably Thailand's best striker of this generation, received his first call-up to the national team in 2007. He has played 99 times for the War Elephants and scored 43 goals.