"Results [are] not a problem; we still have the second-leg and I am sure we can change the game with this one away goal of ours," the German said at the post-match conference.
"I trust my team and we have time to prepare for the return tie."
Refusing to put the blame on his players, Schafer went on to blame the synthetic pitch at the Jalan Besar Stadium and lamented Singapore's luck.
"This field is not ideal and most players have problems playing on it," he bemoaned.
"In the first 15 minutes, Singapore made [us] pressured and many fouls. For the second goal, we were pushed back and [Aleksandar] Duric is the kind of player who knows what to do in that kind of situation.
"The third goal was unfortunate and Singapore had luck today, and I hope we will have luck back in Thailand."
The return leg will be played in the Supachalasai Stadium in Bangkok this Saturday.