World number two Simona Halep says her body was too “tired” to beat Switzerland’s Belinda Bencic in the Dubai Championships quarter-finals.
Bencic, who saved six match points before beating Aryna Sabalenka in the previous round, again showed fight and resilience to win 4-6 6-4 6-2.
Romania’s Halep, 27, saw her serve broken seven times by the 21-year-old.
“I couldn’t serve well because I felt my Achilles, and I had cramping, but there are no excuses,” Halep said.
Halep has played nine matches in the past fortnight after representing Romania in the Fed Cup and reaching the Doha final before going on to compete in Dubai.
“The body felt it was tired and, even though I wasn’t giving up, I felt I didn’t have enough to win. But I played until the end and I tried to stay there.
“I’m not worried about the pain, it is just because I am tired and also had too many matches. I need a few days off and then I will be OK.”
Bencic, ranked 45th in the world, goes on to play Ukraine’s defending champion Elina Svitolina or Spain’s Carla Suarez Navarro, who meet later on Thursday, in the last four.
French Open champion Halep, who is still without a full-time coach after splitting with Australian Darren Cahill last year, was made to pay for missed opportunities in the second set.
After failing to convert a break point to go 3-1 ahead, and another in an eight-minute game for a 4-2 lead, the former world number one lost concentration in the ninth as Bencic broke to love and served out easily for the second set.
That allowed Bencic to continue to grow in confidence, taking control of the points as she won six games in a row to lead 3-0 in the decider.
She regained her double break for a 5-2 advantage and, after a touch of nerves as Halep provided resistance, closed out victory in two hours and 19 minutes.