Kei Nishikori was upset 6-4 6-3 by Thomaz Bellucci at the Rio Open first round.
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.
"Actually everything didn’t work well," said Nishikori. "Probably the condition changed a lot from last week: bounce really high and the balls are really heavy. The ball is the most difficult to adjust. I couldn’t feel anything today. I think it wasn’t my day."