23-year-old Sourabh stunned World No. 13 German Marc Zwiebler, seeded third, 21-15 16-21 21-15 in a men's singles match that lasted 51 minutes.
The Chinese Taipei Open champion Indian will next take on 15th seed Anders Antonsen of Denmark.
His younger brother Sameer, seeded 12th, also disposed off Ukraine's Artem Pochtarov 21-14 21-16 in another quarterfinal match. The Senior National champion will face fourth seeded Chinese Shi Yuqi next.
It was a tooth and nail battle as both Sourabh and Marc moved together right from the start till 7-7 when the Indian opened up a slender 9-7 lead. The German soon caught up but Sourabh broke off at 12-12 and went on to pocket the opening game.
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Sourabh could have sealed the match in the second game itself as he was leading 13-9 at one stage but Marc used all his experience to surpass the Indian with seven straight points and then did not look back as he roared back into the contest.
Sameer, on the other hand, had it easy in the opening game as he erased a slender 0-3 deficit early on and marched ahead without giving any chance to his opponent.
In the second game, Sameer had to fight back from 2-5 and 8-11 down to make it to the final four.