Top seed and French Open runner- up David Ferrer was a stunning quarterfinal loser, while U.S. Open semifinalist Stanislas Wawrinka booked a spot in the semifinals at the $875,500 Malaysian Open tennis event.
Surging Portuguese Joao Sousa recorded the biggest win of his career and reached his second semifinal in two weeks by ousting the Spanish veteran Ferrer in straight sets, 6-2, 7-6 (8-6), on the hardcourts at Putra Indoor Stadium.
"Of course to lose a match is disappointing, but now I'll focus on the next tournament," said Ferrer. "Joao played a great match and that's it. I'll stay positive."
The 77th-ranked Sousa also reached the final four in St. Petersburg, Russia, last week.
"David is a good player," said Sousa. "He probably didn't play his best today, but tennis is like this. Sometimes you have great days, sometimes you don't. I think I played a great match and I'm really happy to be in the semifinals here."
Meanwhile, the world No. 10 Wawrinka came from behind to beat sixth-seeded Russian Dmitry Tursunov 2-6, 6-3, 7-6 (7-3) on Day 5.
In other quarterfinal action, 32-year-old fourth-seeded Austrian left-hander Jurgen Melzer mauled Argentine Federico Delbonis 6-3, 6-2 and fifth-seeded Julien Benneteau foiled fellow Frenchman Adrian Mannarino 6-3, 6-3. Benneteau was last year's Kuala Lumpur runner-up to Argentine Juan Monaco.
Saturday's semis will pit Wawrinka against Benneteau and Melzer versus the giant-killer Sousa.
The 2013 Malaysian Open champion will claim $158,000.