Nigeria U23 team coach Samson Siasia has blamed fatigue caused by the long trip to Korea for their 1-0 loss to the home team on the opening day of the Suwon Invitational Tournament.
The African champions lost to an 86th minute goal scored by South Korea's Choi Kyubaek from a free kick which caught the Nigerian defence –line ball watching.
They play against Denmark, 4-3 winners over Honduras, in their next game on Saturday.
Siasia said his players were not able to play their game as they were still suffering from jet lag occasioned by the long flight from Abuja.
"The flight didn't help matters, but then that is not an excuse for us not getting at least a point from this game,” he said.
"The goal scored by the Koreans was made possible because my players were adopting offside tactics; I don't know where they got that idea from as we have never kept offside in all our trainings and games."
He added: “I am happy the NFF did everything to make us come for this competition as it has exposed the boys to see things from a bigger perspective, even though I wanted us to win this game to boost our confidence.
“The boys now know that they have to sit up in the other games."