China grabbed the first semi-final berth in the Olympic women's hockey tournament on Wednesday, while the Dutch stretched their lead in the pool stage.

Fourth-ranked China steamed past Spain 3-0, their third straight win with no goals conceded.

Only if New Zealand had won all their remaining games could China's first ever Olympic semi-final place have been in jeopardy. But the Kiwis went down 2-0 to Japan later in the day.

"Only three more games to go and we are getting better all the time," said Chinese coach Kim Changback, his sights firmly set on a gold medal. China has one more pool match to play, then the semi-finals and possibly the finals.

Spain attacked strongly, especially in the first half, but China's defence closed ranks, making up for lost scoring opportunities at the other end where the 2002 Champions Trophy winners converted only one of 11 penalty corners.

"There was some problem with cooperation but we'll solve that before the semi-finals," said Chinese forward Tang Chunling. "It's not individuals out there but a great team effort".

The Netherlands, who won back-to-back bronzes at the last two Olympics, routed Germany 4-1 in Pool B.

Two corners and two nifty field goals gave the Dutch a 4-0 lead at half-time but they had to work hard to stop the Germans from turning a second-half rally into more than one goal, blocking the ball and clearing it time and again.

The Dutch are now top of pool B with nine points and an eight-goal difference. Australia, South Korea and Germany can still get nine points but would have to increase their goal rate dramatically to knock the Netherlands out of the semi-finals.

South Korea put their first points on the board on Wednesday, beating South Africa 3-0 in a stodgy game.

They gave only rare glimpses of their flowing hockey in a match that more often saw them crowded around the goal blocking South Africa's shots at the net.

"I'm happy with the result but I'm still unhappy with the quality of the match. (The team) played in a very un-Korean way," said coach Kim Sang-ryul.

South Korea meet defending champions Australia on Friday, when the Pool B semi-finalists could be decided.