Gilles Simon suffered a shock first-round exit at the Shenzhen Open on Tuesday as he was beaten in straight sets by Ricardas Berankis.
Simon, seeded fifth for the ATP 250 event, was outclassed by a player 86 places below him in the rankings, Lithuanian Berankis emerging victorious 6-4 6-2.
French number five Simon won just 50 per cent of points on his first serve and was broken three times by Berankis, whose victory sees him face Lukas Lacko in the next round after the Slovakian beat Russia's Evgeny Donskoy 6-1 7-6 (7-4).
While Simon fell at the first hurdle at the hard-court tournament, there were few problems for the rest of the seeds in action in China as Santiago Giraldo, Vasek Pospisil and Andreas Seppi all went through.
Colombian sixth seed Giraldo was forced to come from behind against Chinese qualifier Bowen Ouyang, who won the first set only to then fall to a 3-6 6-3 6-4 defeat.
Seventh seeded Canadian Pospisil enjoyed an easier day, overcoming Russian Teymuraz Gabashvili 6-3 6-4, and Seppi will now face compatriot Simone Bolelli in the next round after the Italian eighth seed earned a 7-6 (7-3) 6-2 victory over Maximo Gonzalez of Argentina in which he lost just four service points.
Viktor Troicki continued his bid to surge up the rankings following his return from a doping ban with a win as opponent Martin Klizan retired in the third set.
The Serb was leading 5-7 6-1 3-0 in the decider when his Slovakian counterpart withdrew due to injury.
Elsewhere, Gilles Muller racked up 22 aces in a three-set triumph against Marco Chiudinelli, while there were also successes for Australians Sam Groth and Thanasi Kokkinakis.