The 27-year-old Finnish player defeated French seventh seed Toma Junior Popov in the previous round and backed up that victory with a 21-15 21-19 win over Denmark’s world number 12 Gemke.

Koljonen will next face Danish top seed and defending champion Viktor Axelsen who has yet to drop a game as he defeated French eighth seed Thomas Rouxel 21-14 21-15 in the quarter-finals.

"For maybe the first time in my life I am speechless," said Koljonen.

"I have no words right now.

"I feel happy but I need to realise what just happened.

"I think this is some of the best badminton I have ever played.

"I know that sometimes when I find my A game, I can make upsets, and now I have been able to keep the level in a whole tournament, which is not normal for me."

Second seed Anders Antonsen of Denmark struggled past Turkey’s Emre Lale in the last 16 but was back to his best against France’s sixth seed Brice Leverdez, triumphing 21-12 21-13.

Hans-Kristian Solberg Vittinghus will now meet countryman Antonsen in the last four after the fourth seed edged out Dutch fifth seed Mark Caljouw 21-19 17-21 21-15.

Women’s top seed and reigning champion Carolina Marin advanced to the semi-finals after Denmark’s Line Højmark Kjærsfeldt pulled out due to a knee issue.

Turkish fifth seed Neslihan Yiğit overcame German third seed Yvonne Li with a 21-16 21-16 success to set up a last four meeting with Marin.

Scottish number four seed Kirsty Gilmour came from a game down to beat eighth seed Lianne Tan of Belgium 18-21 21-13 21-14.

In an all-Danish quarter-final, seventh seed Line Christophersen produced an impressive display to thump Julie Dawall Jakobsen 21-9 21-8.

Competition is due to continue tomorrow.