World number five Kei Nishikori was dumped out in the first round of the Rio Open by home favourite Thomaz Bellucci.
The top seed went down 6-4 6-3 on the clay in Brazil, having his serve broken four times by Bellucci.
Nishikori's exit opens things up nicely for second seed Dominic Thiem, who progressed past Janko Tipsarevic 6-4 7-5.
2015 champion David Ferrer is out, though, as he lost to Alexandr Dolgopolov in straight sets, but there were victories for Fabio Fognini, Thiago Monteiro, Pablo Carreno Busta, Albert Ramos-Vinolas amd Federico Delbonis.
World number four Milos Raonic enjoyed safe passage to the second round of the Delray Beach Open.
The Canadian, seeded first, breezed past American Tim Smyczek 6-1 6-4 to set up a second-round clash with Borna Coric.
Second seed Ivo Karlovic is out after he was beaten in a tight game by Donald Young, who triumphed 7-6 (7/5) 7-6 (7/3), while third seed Jack Sock is through after a 6-4 7-6 (7/2) win over Radu Albot.
Juan Martin del Potro, Steve Johnson, Steve Darcis, Guillermo Garcia-Lopez and Nikoloz Basilashvilli were also first-round winners.
Frenchmen Nicolas Mahut, Richard Gasquet and Julien Benneteau were among the winners at the Open 13 in Marseille.
Mahut defeated Germany's Alexander Zverev 7-6 (7/5) 7-6 (7/5), Gasquet beat Robin Haase of Holland 6-7 (5/7) 6-3 6-2 and Benneteua defeated Canadian wildcard Denis Shapovalov 7-5 6-4.
Aljaz Bedene of Great Britain, Slovakia's Norbert Gombos, Germany's Jan-Lennard Struff and Ukrainians Illya Marchenko and Sergiy Stakhovsky also advanced.