MARSEILLE (AFP) - World number four and top seed Stefanos Tsitsipas suffered an embarrassing straight sets defeat to 163rd-ranked Russian qualifier Roman Safiullin in the Marseille ATP quarter-finals on Friday (Feb 18).

Safiullin, 24, clinched a memorable 6-4, 6-4 win over his Greek opponent who was runner-up at the French Open last year.

"It's the greatest victory of my career," said the Russian, a former junior Australian Open champion.

"It was my first time in a quarter-final and the first time I have beaten a top 10 player."

Safiullin will meet world number nine and last weekend's Rotterdam champion Felix Auger-Aliassime of Canada in the last-four.

Auger-Aliassime needed six match points to see off Ilya Ivashka of Belarus 6-3, 6-4.

The other semi-final pits second seed Andrey Rublev of Russia against France's Benjamin Bonzi.