Tokyo - Former world number one Angelique Kerber suffered an upset 6-0, 6-7, 6-4 defeat by big-hitting Russian Anastasia Pavlyuchenkova in the Pan Pacific Open semi-finals on Saturday.
Seventh seed Kerber looked in danger of being blown away after losing the first eight games in the Tokyo sunshine.
But the German recovered from 6-0, 5-2 down to pinch the second-set tiebreak as Pavlyuchenkova's game suddenly unravelled, the Russian slamming her racquet to the ground in disgust.
Kerber, who has slipped back to 14th in the world since winning last year's Australian and US Open titles, clinched the breaker 7-4 with a fierce serve down the middle.
The 29-year-old Kerber, a former Tokyo finalist, then quickly raced to a 3-0 lead in the deciding set, only to be pegged back once more.
But Pavlyuchenkova seized the decisive break in the seventh game with a superb backhand drive volley, the same bludgeoning shot she unleashed to seal victory after a little over two hours.
Newly crowned world number one Garbine Muguruza was playing defending champion Caroline Wozniacki in Saturday's second semi-final.