A dominant Stan Wawrinka outclassed Serbian Viktor Troicki to book his place in the semi-finals of the ATP tour's Sofia Open to suggest his recovery from a knee injury is well under way.
The 32-year-old Swiss, who had surgery in August and only returned to the court last month, was in great form in the 6-1 7-6 (7-3) win.
"It was a great match, I played better than I expected," said Wawrinka, aiming to clinch his first title since winning the Geneva Open in May.
"I'm improving every day, I'm moving better and I'm serving better. I think my level is getting better."
Wawrinka's semi-final opponent will be Mirza Basic.
The Bosnian qualifier produced a solid display to beat Maximilian Marterer 6-4 4-6 6-3, claiming his second German scalp after eliminating fourth seed Philipp Kohlschreiber on Wednesday.
World No.93 Marius Copil fired down 13 aces to reach his first ATP semi-final with an impressive 6-4 6-4 victory over third-seeded Gilles Muller.
The Romanian will face Slovakian qualifier Jozef Kovalik, who continued his fairytale week with a 7-6 (7-2) 6-4 win over Cypriot Marcos Baghdatis.
"This is the biggest win of my career," a delighted Kovalik said in a courtside interview.
