Qualifier Steve Darcis produced the upset of the day at the China Open as he downed fourth seed Pablo Carreno Busta in straight sets.
The Belgian - who famously beat Rafael Nadal in the first round of Wimbledon in 2013 - roared to a 6-0 6-4 victory against the world number 10 in Beijing.
Darcis will now face Dusan Lajovic in the second round following the Serbian's 6-1 3-6 6-3 over Carreno Busta's Spanish compatriot Fernando Verdasco.
One Spaniard to emerge unscathed from Monday's action was fifth seed Roberto Bautista Agut, who proved too strong for home hope Zhang Ze in a 6-1 6-3 win.
Next up for Bautista Agut is Aljaz Bedene, who will hope to keep the title on British soil after Andy Murray's triumph in the Chinese capital last year.
Bedene was a 6-4 6-2 winner over Marcel Granollers.
Elsewhere in the draw, Fabio Fognini overcame Robin Haase 7-6 (7-4) 6-2, and Jan-Lennard Struff lost the all-German encounter with Mischa Zverev in three sets.