Defending champions Germany [Images] and the Netherlands swamped opponents after Argentina were held to a draw by United States and former champions Australia [Images] scraped past South Korea in the first round of Olympic [Images] women's hockey on Sunday.

Germany thrashed Britain, ranked 10th and whose last appearance was eight years ago, 5-1 in pool B, while top-ranked Netherlands hammered South Africa [Images] 6-0 in pool A.

A rain-soaked opening day began with Japan [Images] beating New Zealand [Images] 2-1 in pool B following which Asian Games champions China in pool A garnered maximum points against Spain.

"Credit to Germany, I think they were very clinical. First corners were excellent, they took their chances very well," Britain coach Danny Kerry told reporters.

"The scale of defeat hurts a great deal," he added.

Forwards Eileen Hoffmann and Fanny Rinne scored two goals each and Marion Rodewald the other. Crista Cullen was England's [Images] lone success.

"We came into the tournament with the very strong belief that we have to play one game at a time and it is very important that we do that," Britain captain Kate Walsh said.

"We now are going to debrief (about the match) very professionally and thoroughly. There were chances there we didn't take."

Germany's coach Michael Behrmann said the margin was a morale booster but described the match as close.

"The start is good for my team and for me special. I think it was a very close match and we scored at the right time."

The Netherlands pumped in four more goals after leading 2-0 at half-time against the tournament's lowest ranked team with Maartje Paumen finding the back of the net twice.

Argentina, shooting for a first Olympic women's hockey gold, were held two-all in pool B by unfancied US who were reduced to 10 players for nearly 20 minutes in the second half due to yellow card suspensions.

Australia meanwhile fought back from a three-goal deficit in pool A.

The men's first round matches will be played on Monday.

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