He made the remarks after the team arrived in the United Arab Emirates (UAE) to participate in the second round of the 2022 Fifa World Cup Asia zone qualification round from June 3 to 15.
"We have to prepare and select players for the qualification matches, but we have not trained well during 14 days of isolation before departure," he said, adding that all the players had attended a training camp since May 3.
The Thai team will play warm-up matches against Oman on May 25 and against Tajikistan on May 29 before the qualification matches with Indonesia on June 3, the UAE on June 7 and Malaysia on June 15.