Thiem, the talented Austrian and second seed, outclassed Serbia's Dusan Lajovic 6-2 7-5 on the clay courts in Brazil.

The world number eight broke serve three times on his way to the last eight at the ATP 500 event.

Thiem enjoyed a tremendous 2016, particularly on clay – a surface on which he held a 25-7 win-loss record.

Awaiting him in the quarter-finals is Diego Schwartzman, who won an all-Argentine affair against Federico Delbonis 6-4 7-6 (7-1).

The fifth-seeded Ramos-Vinolas was even more comfortable, easing past Italian 2015 runner-up Fabio Fognini 6-2 6-3.

The Spaniard will next face Nicolas Kicker after the Argentinian beat fellow qualifier Arthur De Greef 6-3 6-3.

Belgian De Greef had caused a huge shock in the opening round with a win over defending champion Pablo Cuevas.