Doha - Rank outsider Illya Marchenko continued his remarkable run at the Qatar Open on Thursday overcoming injury and France's Jeremy Chardy to qualify for the semi-finals.
The world-ranked number 94, who knocked defending champion David Ferrer out in the first round, won in straight sets 6-3, 7-6, and now could face Rafael Nadal in the last four.
Chardy is ranked number 31 in the world.
Marchenko, 28, triumphed despite calling for two medical timeouts in the second set and receiving treatment on court from a physio for a back problem.
"My back didn't work so well tonight," said the Ukrainian afterwards. "I hope I am going to be better tomorrow."
Marchenko, who also beat world number 50 Teymuraz Gabashvili in the second round, faces the winner of the Nadal versus Andrey Kuznetsov quarter-final, being played later Thursday.
Prior to beating Ferrer -- the world number seven -- in three sets on Monday, Marchenko had never beaten or taken a set from a top 10-ranked player.