World number one Novak Djokovic suffered a surprise 6-4 6-4 defeat against 15th seed Roberto Bautista Agut in the Shanghai Masters semi-final.
Spaniard Agut, 28, had lost five previous meetings with the Serb, 29.
But the world number 19 took the first set in 42 minutes with his first break point and broke three times in the next one for victory.
Britain's Andy Murray plays world number 32 Gilles Simon of France in the second semi-final on Saturday.