Greek teenager Stefanos Tsitsipas stunned world number seven Dominic Thiem 6-3 6-2 to reach the semi-finals of the Barcelona Open on Friday, while Spain`s Pablo Carreno Busta served up another upset by defeating second seed Grigor Dimitrov.
Tsitsipas and Carreno Busta will face each other on Saturday for a place in Sunday`s final.
The 19-year-old converted four out of eight break points and made Thiem pay for an error-strewn display to prevail in an hour and 20 minutes for the biggest win of his career.
Thiem began the contest strongly and came within a point of going up 3-0 in the opening set but allowed Tsitsipas to fight back. The Greek won a decisive break to go ahead at 5-3 after a double fault by Thiem and then served out the set.
Tsitsipas broke at 2-2 in the second set after more wayward hitting by Thiem and the world number 63 pulled away to seal the match.
World number 11 Carreno Busta, who is seeded fifth in Barcelona, saw off Dimitrov 6-3 7-6(4) in an hour and 37 minutes to reach his second semi-final of the year and level his head-to-head with the Bulgarian at three wins apiece.
World number one Rafa Nadal takes on Slovakia`s Martin Klizan, while Belgian David Goffin faces Spaniard Roberto Bautista Agut in the day`s other quarter-finals.