"There are no easy matches in this tournament; the level is extremely high," Feghouli is quoted as saying by FIFA.com.
"We're going to give 100% versus the South Koreans. It's often little things that make the difference, as we saw in the Belgium match. At this level, tiny mistakes can cost you dearly.
"We're now very focused and plan to play in a different way, causing them problems and looking for the win."
Feghouli has scored six goals in 18 games for Algeria since making his debut in 2011.