Americans Jake Gibb and Sean Rosenthal lost to Poland in pool play Monday night, the first loss for the American men or women in beach volleyball at the London Olympics.
Grzegorz Fijalek and Mariusz Prudel, the No. 7 team in the Olympic rankings, beat the Americans 21-17, 21-18. The U.S. team is 1-1 in pool play with one remaining match on Wednesday; they might not need to win, but a victory could be necessary to avoid relegation to a "lucky loser'' playoff.
"It is a big game against Latvia,'' Rosenthal said. "We'll be ready.''
Defending gold medalists Kerri Walsh Jennings and Misty May-Treanor played later Monday, with the U.S. men's basketball team showing up to watch.
The Americans had beaten the Polish pair in straight sets at the Berlin Grand Slam event in mid-July.
"They made some big adjustments from the last time we played them,'' Gibb said.
Fijalek said it was obvious they needed to make changes if they were going to compete with the Americans, who were No. 4 in the world coming into the games.
"Of course, because we lost very easy in Berlin,'' he said. "We watched that game many times. We played new beach volleyball.''
Earlier in the night session, Sascha Heyer and Sebastian Chevallier beat Russia on a disputed call that ended with Russian Konstantin Semenov arguing with the referee and drawing a yellow card.
After winning a 31-minute first set -- as long as some entire matches -- 28-26, the Swiss lost the second 21-18. They trailed 13-11 in the 15-point third set before scoring three straight points.
On set point, Heyer's serve went untouched to the deep part of the court, and the linesman signaled it out. But the referee climbed down from her stand, walked over to examine the ball mark, climbed back to her stand, and signaled the winning point for the Swiss.
Semenov began arguing and didn't stop, even after the referee, Catriona Tweedie of Austria, held up the yellow card. Points can be awarded the other team for yellow cards, but at the end of the match it is meaningless.
"I'm not happy at all with the decision of the judge,'' said the other Russian, Serguei Prokopiev. "We play at such a high level, and this has happened before.''
The Swiss also thought it was out until seeing the replay.
"I went back to get the next (serve), but suddenly my partner comes up to me and starts hugging me,'' Chevallier said. "Now we were lucky, and maybe two days from now we'll be unlucky.''
Earlier Monday, defending bronze medalists Zhang Xi and Xue Chen recovered from an opening loss to beat Switzerland. The Chinese pair was upset in the very first match at Horse Guards Parade but would likely advance with a victory over Greece on Wednesday.
In other women's action Monday, medal favorites Juliana and Larissa of Brazil beat Katrin Holtwick and Ilka Semmler of Germany and Czechs Hana Klapalova and Lenka Hajeckova beat Natacha Rigobert and Elodie Li Yuk Lo of Mauritius also won in two sets. Maria Tsiartsiani and Vasiliki Arvaniti of Greece beat Russia's Anastasia Vasina and Anna Vozakova 18-21, 21-13, 15-12.
In the men's competition, straight set victories went to Martin Spinnangr and Tarjei Viken Skarlund of Norway over Canadians Joshua Binstock and Martin Reader; Aleksandrs Samoilovs and Ruslans Sorokins of Latvia over Freedom Chiya and Grant Goldschmidt of South Africa and Ricardo Santos and Pedro Cunha of Brazil over Britain's Steve Grotowski and John Garcia-Thompson. Germany's Julius Brink and Jonas Reckermann beat Wu Penggen and Xu Linyin of China 13-21, 21-19, 15-8.