One of the favourites for the tournament, his withdrawal gave Croatia's Tomislav Pucar a walkover victory and a place in the quarter-finals. 

Ovtcharov's team-mate Timo Boll has also made it through to the next round after a 4-1 win over Sweden's Kristian Karlsson.

World number eight Mattias Falck of Sweden made it through to the quarter-finals too after defeating France’s Emmanuel Lebesson 4-2.

Two surprise defeats came for France’s Simon Gauzy and Belarus’ Vladimir Samsonov, who were knocked out by Slovakia’s Wang Yang and Slovenia’s Darko Jorgic respectively.

In the women’s event, Germany’s world number 19 Petrissa Solja shut out Polish last-16 opponent Natalia Partyka in straight sets.

The big shock in the opening round came when Romania’s Bernadette Szocs was beaten in five sets against world number 47 Britt Eerland.

The European number one, Sofia Polcanova of Austria, also made it through to the quarter-finals along with Germany’s Han Ying.

In the quarters, Jorgic and Wang met for a place in the semi-finals, with the Slovenian coming out in a 4-1 win that saw the final set reach 22-20.

Boll won in straight sets against England's Liam Pitchford while Pucar won in a 4-2 defeat of Portugal's Marcos Freitas.

Falck was upsetted by one of the lowest seeds in the competition when world number 36 Robert Gardos of Austria came from 2-1 down to win 4-2.

In the women's quarters, top seed Polcanova eased to victory against Slovakia's Barbora Balazova in straight sets with Solja making it through too after a 4-2 win over Romania's Elizabeta Samara. 

Dutch player Eerland made the final four, but fourth seed Han will not progress after a seven-set thriller loss to Margaryta Pesotska.