Poland's Michal Bryl and Kacper Kujawiak caused a shock in the men's competition as the main draw got underway at the International Volleyball Federation (FIVB) World Tour Xiamen Open in China.
The qualifiers were too strong for sixth seeds and Fuzhou Open champions Paolo Nicolai and Daniele Lupo although they needed three sets to beat the Italians.
They fought back from 11-5 down in the second to win 22-24, 21-18, 15-12 in Pool F as rain made play difficult.
"We are very, very happy to win this match," said Bryl, one half of the 27th ranked team in the 32-strong draw.
"We just kept going and never gave up.
"The second set was very important to us, because we were able to come back from 11-5 down.
"If we gave up, the game was over."
Latvia's Aleksandrs Samoilovs and Janis Smedins had a good day as they eased to a pair of victories.
Last year's Xiamen bronze medallists beat China's Lin Wuqin and Lu Zequan 21-13, 21-17 before sweeping past Canada’s Sam Pedlow and Grant O’Gorman 21-15, 21-15.
Number 24 seeds Thomas Kunert and Christoph Dressler from Austria also enjoyed an upset win, beating China's eighth ranked Chen Cheng and Zhang Lizeng 33-31, 21-18 after a mammoth first set in Pool H.
Australian's Cole Durant and Bo Soderberg, ranked 25th, also collected a notable win in Pool H as they beat Mexicans Juan Virgen and Lombardo Ontivero, the ninth seeds, 21-16, 21-15.
Thirty-two teams are playing round robins in eight groups with the top three finishers from each pool qualifying for the single elimination knock-out stage.
The women's main draw will begin tomorrow with German and American teams claiming half of the eight places on offer.