Brazilian Thomaz Bellucci has upset top-seeded Kei Nishikori 6-4 6-3 in the first round of the Rio Open.

World No.5 Nishikori, who lost the Argentina Open final on Sunday, smashed his racquet on the claycourt after losing Tuesday’s (Wednesday’s AEDT) first set.

It didn’t get any better. He was broken in the first game of the second and never recovered.

Bellucci, the world No.76, had lost his previous two matches against Nishikori, who has lost all six of his singles finals since winning the Memphis Open a year ago.

In another first-round match, fourth-seeded Pablo Carreno Busta of Spain defeated Brazil’s Joao Souza 6-3 6-2.