Tomas Berdych suffered a surprise defeat in his opening match at the China Open as he was beaten in straight sets by Pablo Cuevas.
Berdych – the second seed in Beijing – came into the tournament having won in Shenzhen last weekend, and is the highest-ranked player yet to secure a place at the ATP World Tour Finals in London.
However, his game was strewn with mistakes against the world number 37, the Czech making 32 unforced errors as he was dumped out 6-4 6-4.
In Wednesday's only other first-round match, Cuevas' next opponent Ivo Karlovic fired down 19 aces on his way to a 7-5 7-6 (7-1) win over Guillermo Garcia-Lopez – moving him just 16 short of Goran Ivanisevic's record of 10,237 aces.
While Berdych missed out on crucial points in the race to be in London next month, third seed Rafael Nadal moved closer to confirming his place as he booked a quarter-final spot.
Vasek Pospisil pushed Nadal in a tough encounter for the 14-time grand slam winner, but Nadal was able to find the quality when he needed it.
Having wasted a set point in the final game of the first, Nadal dominated the tie-break before controlling the second to come through 7-6 (7-3) 6-4 in just under two hours on court.
The Spaniard will meet Jack Sock in the last eight after the American cruised past Andreas Haider-Maurer 6-3 6-1.
Meanwhile, David Ferrer will meet wildcard Lu Yen-hsun in the only other confirmed quarter-final after both men recorded straight-set wins.
Ferrer beat Lukas Rosol 7-6 (7-5) 6-2, while Lu saved three break points on his way to knocking Viktor Troicki out 6-4 7-5.