Ivo Karlovic and Bernard Tomic remain on course for a re-match of their 2014 Claro Open Colombia final after second-round wins.
The top four seeds all won through to the Claro Open Colombia quarter-finals on Thursday, but each of Ivo Karlovic, Bernard Tomic and Victor Estrella Burgos were tested.
Karlovic, Tomic and Estrella Burgos were three of the four semi-finalists in Bogota in 2014 - Radek Stepanek the other - and they preserved their runs at the ATP 250 hard-court event with three-set triumphs.
Croatian top seed Karlovic dropped a set to world number 607 Daniel Elahi Galan, but that was the best it got for the Colombian wildcard as Karlovic earned a 6-7 (12-14) 6-1 6-3 victory.
Tomic, seeded two, similarly overcame Adrian Menendez-Maceiras 6-7 (5-7) 6-2 6-4, while fourth seed Estrella Burgos also dropped a tie-break in his 6-4 6-7 (4-7) 6-2 win over Yuichi Sugita.
Third seed Adrian Mannarino ended Rajeev Ram's winning run at six matches, the lefty prevailing 7-5 6-3.
Wildcard Stepanek will face Karlovic for the first time since their semi-final clash 12 months earlier, after the Czech ousted sixth seed Sam Groth 6-4 6-0.
Inactivity has seen Stepanek's ranking drop from 39th at the same stage last season to 369th.
Malek Jaziri, the seventh seed, surpassed American qualifier Alexander Sarkissian 6-7 (1-7) 6-3 6-2, while other qualifiers Marcelo Demoliner and Alejandro Gomez were also valiant losers.
Michael Berrer saw off Brazil's Demoliner 6-3 7-6 (7-3), while Colombian Gomez was no match for Tatsuma Ito 6-1 5-7 6-0.