Rio de Janeiro, Brazil (SportsNetwork.com) - Former top-10 star Tommy Robredo came up a second-round loser Wednesday at the $1.55 million Rio Open tennis event.

Austrian Andreas Haider-Maurer upset the third-seeded Spaniard 6-3, 6-2 on the red clay at Jockey Club Brasileiro.

"It was a great win for me, for sure," said Haider-Maurer. "I played well against Tommy Robredo, and I'm very happy... Every round here is very important. Every round is a big step. I made for the first time the quarterfinals at an ATP 500."

The world No. 18 Robredo is the No. 3 active clay-court wins leader behind only Rafael Nadal and David Ferrer.

Meanwhile, former top-10 Argentine Juan Monaco got past 33-year-old Finnish veteran Jarkko Nieminen 6-1, 7-6 (7-4).

In some more second-round action here on Thursday, the top-seeded superstar Nadal will take on fellow Spaniard Pablo Carreno Busta. The reigning Rio champion Nadal topped Ukrainian Alexandr Dolgopolov in last year's inaugural Rio finale.

The 2015 champ will pocket $343,000.