South Korea ranked 17th in the world, and Morocco, ranked 76th, both had lost their first matches before they met off on Sunday.
Ibtissam Jradi scored Morocco's first-ever goal in a women's world cup in just six minutes, startling the team that finished second in the Asian Cup.
The early goal gave the Moroccans a spring in their step, and they continued to impress early on, with Jradi continuing to dazzle with her work rate and link-up play.
South Korea gained possession but struggled to produce chances, as Morocco defended tenaciously when pushed back into their half.
The second half was a one-sided drama under heavy pressure. With time running out, South Korea's greatest opportunity of the game fell to Casey Phair, a 16-year-old who controlled the area superbly before dragging her shot wide of the post.
Morocco threatened on the break into added time, with Tottenham's Rosella Ayane squandering a late chance, but they didn't need a second. South Korea will be eliminated if Germany does not lose to Colombia later today.">