Reigning Rio Open champion Dominic Thiem cruised through to the round of 16 on Tuesday, while Gael Monfils survived his first-round encounter.
Thiem – the second seed – accounted for Serbian Dusan Lajovic 6-2 7-5 on the clay courts in Rio de Janeiro.
Running hot after winning his second Argentina Open last week, Thiem continued his fine form on clay as he converted four of 11 break points.
Next up for the Austrian star is Pablo Andujar, who was too good for Gerald Melzer 7-5 6-2 at the ATP 500 tournament.
Entertaining Frenchman Monfils was forced to dig deep en route to the last 16 after saving a match point against Horacio Zeballos.
Zeballos led 5-2 in the third and deciding set and served for it at 5-3 but Monfils reeled off five successive games to triumph 7-5 3-6 7-5.
It does not get any easier for the unseeded Monfils – a semi-finalist at the Argentina Open.
Top seed and Australian Open runner-up Marin Cilic stands in the way of Monfils and a spot in the quarter-finals.
It was a good day for seeds, with Pablo Carreno Busta, Diego Schwartzman and Pablo Cuevas all progressing.
Spanish third seed Carreno Busta defeated Marco Cecchinato 6-4 6-1, Schwartzman – the sixth seed – was leading 4-1 when Casper Ruud retired, while seventh seed Cuevas outlasted wildcard Thiago Monteiro 6-7 (5-7) 7-6 (12-10) 6-3.
Federico Delbonis celebrated his 100th tour-level victory after Jiri Vesely retired down 6-2 3-2, Aljaz Bedene beat Andreas Haider-Maurer 7-5 6-0 and Nicolas Kicker topped Victor Estrella Burgos 6-3 6-3.
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