Australia topped their pool in the women's field hockey World Cup on Saturday following a 4-3 win over South Korea after Argentina drew 2-2 with South Africa.
Argentina dropped crucial points to leave Australia the clear group leaders with nine points.
In the day's other match, Japan and the US drew 0-0 in a crucial game for both sides as neither had earned any points from their two previous matches.
Australia maintained their unbeaten record with a victory over a feisty and desperate South Korea in an entertaining match.
South Korea went into the encounter with four points from two matches and had to win to keep their top four hopes alive.
Australian coach Frank Murray admitted that his team had gained respect for its opponents.
"This was a crunch match for us today, we rate Korea highly and I am very pleased we came away with the points," Murray said.
"It still is not enough to guarantee us a semi [final]) berth. We believe we need at least one more point from the next two games and a good goal difference to go through," he said.
South Korea started at a furious pace in a bid to rattle Australia.
Australia responded with long passes and put Korea's resolve to the test, and in the second half South Korea was reduced to running all over the field as Australia threw the ball from stick to stick.
Then Park Mi Hyun scored on a corner deflection and Australia had to survive a torrid final five minutes to win and remain undefeated.
Argentina scored first against South Africa on a penalty corner in the 29th minute by Mercedes Margalot that shaved the left post.
A precision corner goal was scored against the run of play by Jen Wilson for South Africa just after half-time. Wilson then picked up a pass in another corner move and won a penalty stroke which was converted by Tarryn Bright.
With Lenise Marais keeping Argentine star Luciana Aymar quiet, South Africa sensed victory.
However, with three minutes remaining, Rosario Luchetti lobbed in a goal that provided the equalizing point. South Africa then held on for a draw and their second point in the tournament.
In the other match, Japan took the game to the US and showed better technical skills. The 0-0 draw leaves both teams seemingly destined for the 9-12 playoffs.