Sam Deroo scored 15 points for the Belgians in the 25-20, 25-18, 25-23 triumph, which left the home crowd in Novi Sad stunned.

Victory moves Belgium above Serbia in the Pool B1 Group One standings and level on four points with leaders Canada, who overcame the United States 23-25, 25-19, 18-25, 25-23, 15-11 today.

The Canadians are competing in the top-tier of the FIVB World League for the first time and now have two wins to their name having beaten Belgium yesterday.

In Pool A1 Group One, Poland maintained their perfect start to the season after beating hosts Italy in four sets in Pesaro.

Having defeated 2016 runners-up Brazil yesterday, the Poles claimed a 21-25, 25-17, 25-18, 25-23 win over their European counterparts.

Dawid Konarski led Poland’s scoring with 17 points - 12 from spikes and five from blocks.

Captain Michal Kubiak added 13 points for the 2014 world champions, while Filippo Lanza put 14 points on the board for Italy.

Brazil bounced back from their defeat at the hands of Poland to beat Iran 21-25, 25-19, 25-22, 25-22.

Action also continued today in Pool C1 Group One in Kazan, where hosts Russia lost 13-25, 20-25, 25-22, 21-25 to last year’s bronze medallists France.

France now have six points, while Russia have three and Argentina, 25-23, 23-25, 20-25, 25-21, 15-12 winners at the expense of Bulgaria today, have two.

Competition in Pools A1, B1 and C1 is due to conclude tomorrow.

Pool A1 sees Italy meet Brazil and Poland face Iran, while Pool B1’s line-up features matches between the US and Belgium and Canada and Serbia.

Argentina and France clash in Pool C1 which also pits Russia against Bulgaria.

The 2017 Group One finals are due to take place in Brazilian city Curitiba from July 4 to 8.