British No 2 Heather Watson toiled to a 6-3 1-6 6-1 victory to book her place in the last four of the Mexican Open.
The Briton took on world No 86 Christina McHale for a chance to play Xiyu Wang and looked comfortable as she wrapped up the opening set inside 39 minutes.
A pair of breaks for the American saw Watson on the wrong end of a 5-1 scoreline in the second set with McHale converting her first set point to force a decider.
However Watson proved too good in the third, breaking for 3-1 and 5-1 before serving out the match.
In the men's draw, Kyle Edmund lost his quarter-final clash with American Taylor Fritz in straight sets 6-4 6-3.
Fritz recorded 11 aces during the tie, with a break at 5-4 seeing the Briton lose the first set and two consecutive dropped service games in the second proving costly.
"When Kyle and I play each other, it's all about who is going to get the first big shot in," Fritz said.
"Even when I was nervous, I was telling myself to still go for my shots."
Top seed Rafael Nadal continued his serene passage through the draw by beating South Korea's Soon-woo Kwon 6-2 6-1 in their quarter-final.
Nadal has dropped just 15 games in his first three rounds as he closes in on a third victory in the event and first since 2013.
"The match has been much tougher than what the result said," Nadal said. "It was a good match against a tough opponent. I think he's going to have a very good tennis career."
Nadal will face Grigor Dimitrov in the semi-finals after Dimitrov beat third seed Stan Wawrinka 6-4 6-4. The other semi-final sees John Isner face Fritz after their wins over Tommy Paul and Edmund respectively.
World No 1 Ashleigh Barty completed the Qatar Open semi-final line-up, with a hard-fought victory over two-time Grand Slam champion Garbine Muguruza.
The Australian lost the second set on a tie-break, but won her last eight clash 6-1 6-7 (4-7) 6-2 in Doha.
Up next for Barty, after her one hour and 51 minute encounter, is a match with 29-year-old Petra Kvitova. Kvitova, a two-time Wimbledon winner, held her nerve against Tunisia's Ons Jabeur to win 7-6 (7-2) 7-6 (7-4).
The unseeded Svetlana Kuznetsova rolled back the years to stun fourth seed Belinda Bencic and book a semi-final berth with a 6-4 6-4 victory. It was not so straightforward for Aryna Sabalenka, after she needed two hours and 20 minutes to defeat Zheng Saisai 3-6 7-6 (7-2) 6-3.
Check our news, reports and reaction from all major tennis events by following us on skysports.com/tennis, our app for mobile devices or our Twitter account @skysportstennis.