Nicolas Almagro and Pablo Cuevas reached the Brasil Open second round with gritty wins in Sao Paulo on Monday.
Spaniard Almagro, a three-time champion who is unseeded at the ATP 250 event played on clay, overcame Blaz Rola 7-6 (7-3) 6-4.
Almagro sent down 10 aces in his win, but he was tested towards the end of both sets.
He eventually got the job done in one hour 38 minutes, setting up a clash with countryman and second seed Tommy Robredo.
Almagro saved a break point in the fourth game of the first set and games were on serve until the 11th - the former world number nine breaking to love.
But he failed to serve out the set, only to respond to that disappointment by winning six of the first seven points in the tie-break.
The only break of the second set came at the perfect time for Almagro, the 10th game seeing him secure victory as Slovenian Rola served to stay in it.
Uruguayan fifth seed Cuevas overcame talented Czech Jiri Vesely 6-4 3-6 7-5.
Vesely had looked on track for victory when he broke for 5-4 in the third, but the left-hander was broken straight back and then gave up his serve again in the 12th game to bow out.
Cuevas will meet an Argentine in the second round, with either Facundo Bagnis or Federico Delbonis awaiting him.
In the day's other match, Spaniard Albert Ramos beat Brazil's Guilherme Clezar 7-5 7-5.