German duo Julius Thole and Clemens Wickler progressed to the last 16 of the men's International Volleyball Federation (FIVB) Beach World Tour in Warsaw after fourth seeds Nicholas Lucena and Philip Dalhausser were forced to withdraw from their Pool D match.
The 13th seeds led their American rivals 21-13, 4-2 when Dalhausser complained of discomfort in his abdominal muscles.
Thole and Wickler will face Russia's Nikita Liamin and Taras Myskiv in round two tomorrow after they fought back to defeat Americans Trevor Crabb and Tri Bourne 20-22, 21-19, 15-10.
Polish third seeds Viacheslav Krasilnikov and Oleg Stoyanovskiy won their first elimination match against Swiss pair Adrian Heidrich and Mirco Gerson 21-14, 21-17 after succumbing to Brazilian duo Alison Cerutti and Alvaro Morais Filho in a tense three-setter in Pool C.
Cerutti and Morais Filho progressed as Pool C winners with a 21-18, 17-21, 15-12 triumph after almost an hour of play.
In Pool F, Evandro Goncalves Oliveira Junior and Bruno Oscar Schmidt stunned sixth seeds Paolo Nicolai and Daniele Lupo of Italy as they sealed a 21-16, 21-18 win.
The Italians joined their Brazilian rivals in round two with a straight sets 21-16, 21-19 win against Canadians Grant O'Gorman and Ben Saxton.
Defending champion Piotr Kantor of Poland and his team mate Mariusz Prudel won 23-21, 21-14 against Chilean cousins Marco and Esteban Grimalt to top Pool H.
Home favourites Grzegorz Fijalek and Michal Bryl won Pool A with a 21-18, 21-16 triumph against Brazil’s Pedro Solberg and Vitor Goncalves Felipe.
Norway’s Anders Mol and Christian Sørum hold the number one spot in the world rankings and managed a 24-22, 21-16 victory against Theodore Brunner and William Reid Priddy from the United States in Pool B.
Women's third seeds Agatha Bednarczuk and Eduarda Santos Lisboa battled back from a set down to defeat Canadian pair Sarah Pavan and Melissa Humana-Paredes 16-21, 21-13, 15-12 to reach tomorrow's semi-finals.
They will face Americans Emily Stockman and Kelley Larsen after the duo breezed to a 21-13, 21-14 victory against compatriots Alexandra Klinemann and April Ross.
Australians Mariafe Artacho and Taliqua Clancy reached the last four with a 21-15, 18-21, 15-13 triumph against Brazilians Ana Patricia Silva Ramos and Rebecca Cavalcanti Barbosa Silva.
They will face Carolina Solberg Salgado and Maria Antonelli tomorrow after the Brazilians edged a tight round-three clash 21-19, 21-19 against Russian duo Nadezda Makroguzova and Svetlana Kholomina.