Top seed Kei Nishikori fell at the first hurdle against local favourite Thomaz Bellucci at the Rio Open and he was not the only casualty in Brazil.

World number five Nishikori was outplayed by Brazilian Bellucci, who emerged victorious 6-4 6-3 in the first-round encounter on the clay in Rio de Janeiro on Tuesday.

Runner-up at the Argentina Open last week, Nishikori saved three break points but was broken on four occasions as he was bundled out in one hour, 19 minutes.

Bellucci will face countryman Thiago Monteiro in the second round.

Monteiro was too good for Gastao Elias 2-6 7-6 (7-4) 6-4.

Nishikori was not the only seed to fall on Tuesday, with David Ferrer and Paolo Lorenzi also crashing out in the first round.

Spanish veteran and sixth seed Ferrer went down to Alexandr Dolgopolov 6-4 6-4, while Lorenzi was outlasted by Federico Delbonis 4-6 6-1 6-4.

Dominic Thiem, Pablo Carreno Busta and Albert Ramos-Vinolas, however, had no such trouble reaching the second round.

Austrian second seed Thiem accounted for Janko Tipsarevic 6-4 7-5, Carreno Busta - the fourth seed - defeated Joao Souza 6-3 6-2 and fifth seed Ramos-Vinolas saw off Stephane Robert 6-2 6-0.

Victor Estrella Burgos beat Guido Pella 6-2 7-5, Fabio Fognini was a 6-2 6-4 winner over Tommy Robredo and Horacio Zeballos trumped Carlos Berlocq 6-2 6-3 in their all-Argentine affair.