Great Britain 1 Germany 5
Defensive errors cost Great Britain's women dearly as they lost 5-1 to Germany in the opening match of their Olympic campaign.
With world number twos Argentina being held to a surprise 2-2 draw by the USA in Pool B, a result against the defending champions would have been an important step towards qualification for the semi-finals.
But despite creating a number of chances they were not as sharp in front of goal as their opponents, whom they beat 4-1 in a warm-up match in Dublin last month.
Great Britain have now not beaten Germany in a major tournament since the 1996 Olympics in Atlanta.
Early on Bowdon Hightown's Jo Ellis was denied from five yards by goalkeeper Kristina Reynolds while Anne Panter's 13th-minute strike from the top of the circle was deflected wide.
However, a mistake by Beth Storry conceded the lead as from Germany's first penalty corner in the 26th minute the goalkeeper flapped at Fanny Rinne's head-high drag-flick which went straight down the middle of the goal and into the net.
GB responded with a short corner of their own two minutes later and Leicester defender Crista Cullen's low effort beat Reynolds low to her left.
Parity lasted three minutes as slack defending allowed Mandy Haase to take a quick free-hit on the left which travelled across the circle to an unmarked Eileen Hoffman at the far post who converted a simple deflection.
In the 33rd minute another Cullen penalty corner was saved and the Leicester defender fired the rebound wide.
GB were much more positive in the second half and in the 47th minute Leicester midfielder Jennie Bimson was only inches wide with a diving deflection.But just a minute later the unmarked Hoffman scored a second tap-in, this time from a penalty corner, to end the revival.
Then Maike Stoeckel cut the ball back from the left byline for Rinne to fire home her second. Panter then missed the ball in front of an open goal before Marion Rodewald drilled home a reverse-stick effort after Storry had tipped Katharina Scholz's shot onto a post.
Head coach Danny Kerry admitted the defeat had been a painful one.
"Credit to Germany, they were very clinical and took their chances very well but the scale of the defeat hurts a great deal," he said. "I think the players know we were off our game in a few areas and we will look hard at that."
Captain Kate Walsh added: "We had some chances and if at 2-1 we could have brought it back to 2-2 we would have been in with a shout.
"It was that next goal which was crucial and I think once the Germans get a roll on they make it very difficult.
"It was disappointing because we unpicked them at times and it was just scoring those chances when we had them."
Earlier, in Britain's group, Japan beat New Zealand 2-1.