Suwon Bluewings coach Cha Bum-kun rued a missed opportunity after his side lost 2-1 at Gamba Osaka in the Asian Champions League overnight.
The Korean outfit had a great chance to grab at least a point and remain on top of the Group G table but they fell to the Japanese club and now risk missing out on a home fixture in the Round of 16.
"I thought we were heading home with one point in our hand," said Cha.
"But our players seemed to have lost their concentration in the last part of the game. We gave up their first goal so easily and so soon after our first goal, and that hurt us.
"We want to play at home in the round of 16 and played for three points today but with the result, that possibility seems to have become smaller.
"Our players must learn today that they should play to the very end of the game until they hear the final whistle without losing their concentration. I hope our players use this experience and won't repeat their mistakes," he added.
Suwon take on Singapore Armed Forces at home in their final group stage match as Gamba are away to Chinese club Henan Jianye.