Defending champion Paul Casey crashed out of the HSBC World Match Play after a 4&3 loss to Argentine Angel Cabrera.
Big-hitting Cabrera won his maiden major at the US Open this year
The 30-year-old Englishman trailed by one after the first 18 holes and US Open champion Cabrera stretched ahead with five birdies in the afternoon.
Six-time winner Ernie Els beat Argentine Andres Romero by 6&5.
Swede Henrik Stenson downed Anders Hansen 7&6 despite the Dane's hole-in-one at the 28th hole, while Hunter Mahan beat Soren Hansen by 6&4.
The 37-year-old Cabrera, who won the PGA Championship at Wentworth in 2005, will take on American Mahan in the semi-final.
"I lipped out too many putts," said Casey. "But he played fine golf and was always going to be tough to beat.
"He didn't give me anything, but that's the way it goes and I really hope he goes on and wins it now."
Els is jetting to Paris on Sunday to watch South Africa play rugby
Els was four up after the first round and reached as much as seven up after the 10th against Romero, who finished third in the Open at Carnoustie.
The South African will play Accenture Match Play champion Stenson in the second semi-final.
"I played well when I needed to," Els said. "But he didn't have his best day. I was fortunate to be four up at lunch and my short game definitely saved me. But all in all, I've got to be happy with the way things have gone."
Stenson added: "It will be a tough weekend, playing Ernie, the six times winner who re-designed the course - he even lives here. Are there any more advantages we can give him?"
Stenson and Romero began the day by finishing off their held-over first-round matches, with Stenson beating American Woody Austin on the 18th and Romero downing Swede Niclas Fasth 3&2.
Els or Stenson could go top of the European Order of Merit this weekend following the exits of leading pair Padraig Harrington and Justin Rose on the opening day.