LONDON Britain's Kate Walsh returned to play on Saturday just six days after breaking her jaw, but even the skipper's comeback could not save her team from a surprise 2-1 defeat against China that dealt a blow to the host's Olympic hopes.
Britain, who had won their first three matches, now need at least a draw in their last group-stage match against the Netherlands, who have already secured a berth in the semifinals.
With a slew of unforced errors and little determination in attack, Britain found it hard to penetrate China's defense, and six minutes before half time Walsh and fellow corner-specialist Crista Cullen wasted four consecutive penalty corners.
While at the break it still looked as though Britain's worst performance so far might have been enough against a Chinese side showing little ambition in attack, China came back stronger from the interlude and were clinical on set pieces.
Two goals from penalty corners, one by Fu Baorong in the 41st minute and one deflected into goal from short range by Zhao Yudiao, put China well in the lead with 24 minutes to go.
Just over a minute before the end, Britain reduced the lead with a penalty corner flick from Cullen that the strong Chinese goalkeeper Zhang Yimeng got her hands on but could not save.
"We know we can play a lot better. Ball retention was pretty poor for us today," said Walsh, who played with protective strapping on her face after having a titanium plate inserted into her jaw on Monday and only leaving hospital on Wednesday.
In Saturday's match, British midfielder Anne Panter was also hit by a lifted ball and was led off the pitch with blood dripping from her mouth. But she came back in the second half, having received stitches for the wound.
London's Olympic Games have been unusually hazardous for hockey, a sport in which most body contact is penalized but where the small and fast-travelling ball and stick contact can cause brutal injuries.
Spain's men, Beijing silver medalists, have already lost skipper Santi Freixa and striker Pol Amat, who are out with a broken arm and a dislocated shoulder.
Britain's surprise defeat on Saturday means China are trailing them by two points and could go through to the semifinals if the home team lose against the Dutch.
The Netherlands have already qualified ahead of their game against Britain, having won all four matches so far, though they looked patchy at times in their 3-2 victory over South Korea.
In Group B, Germany's bid to reach the last four stumbled while Argentina, who showed unexpected weakness in their defeat to the United States earlier this week, New Zealand and Australia kept their dreams of reaching the semifinals alive.
Argentina pushed hard through much of their game against Germany, forcing the Germans into some nervy mistakes, which paid off in the 13th minute in a messy situation in front of Germany's goal.
Defender Katharina Otte could not control a pass from Argentina's Rocio Sanchez Moccia near the German goal, leaving Sofia Maccari to roll the ball over the line.
Argentina then wasted a series of corners before their skipper Luciana Aymar showed why she has won a record seven player of the year awards. In a penalty corner variation, she lifted the ball over a defender's stick to slam it into the German board for a deserved 2-0 half time lead.
Germany came back in the last 15 minutes of the match but the country's flagbearer Natascha Keller and her fellow strikers could not overcome Argentina's goalkeeper Florencia Mutio.
Germany's Nina Hasselmann scored a 64th minute goal from the fourth rebound of a penalty corner, but left the back door completely open on a quick break by Argentina less than a minute later, which Sanchez Moccia netted for the 3-1 final result.
An exciting see-saw struggle between New Zealand and the United States, which the Kiwis finally won 3-2, puts them, Australia and Argentina on nine points, with the South Americans leading Group B on goal difference with just one match to go.
(Editing by Matt Falloon)