The two-time champions needed a hard-fought display to edge past Oman in Canberra, with Cho Young-cheol securing the three points with the only goal in first-half stoppage time.
Stielike admitted his side had not been at their most fluent on Saturday, but knows they have plenty more to give as they go further in the competition.
"I prefer to start this way, a hard game, a tough game, and a narrow result," said the German head coach.
"Rather than winning 5-0, we can learn from the mistakes and get better and better in the tournament.
"We can play better over 90 minutes, but I think more like the way we played in the second half, we had strong 15 to 20 minute spells when Oman were not coming out of their half and we missed many chances."
South Korea face Kuwait next in the group – in Canberra on Tuesday – and Stielike insists their focus is on that game, rather than their mouth-watering clash with hosts Australia in Brisbane four days later.
He added: "First we play Kuwait, we are not thinking of Australia we have a short time for preparation. This is a big handicap, one day more or one day less in a tournament, it is very hard for your team."
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