Marcos Giron survived a scare against qualifier Alex Rybakov in the opening round of the Dallas Open on Tuesday, escaping with a 6-4 6-7 (1-7) 6-1 victory.

One of the top seeds in action, Giron is ranked over 300 spots higher than Rybakov, but the underdog put up a serious fight and held up well in all key indicators.

Rybakov had 29 winners with only 17 unforced errors, and he had just two double faults to go with seven aces, but Giron was better in both categories. His talent shone through with 34 winners and 16 unforced errors, while he also had 10 aces and no double faults.

Also in Dallas, French eighth seed Adrian Mannarino secured a 7-6 (8-6) 6-2 win against Steve Johnson, and he will now face Australia's Jordan Thompson following his 6-1 7-5 triumph over Denis Kudla.

Meanwhile, at the Cordoba Open, Argentina's Federico Coria was the top seed to advance after defeating Brazil's Thiago Monteiro 6-7 (5-7) 6-1 6-2.

There was less success for hometown seventh seed Pedro Martinez, who was eliminated 7-6 (7-3) 2-6 6-0 by Chile's Cristian Garin, while Federico Delbonis beat Alejandro Tabilo 6-7 (8-10) 6-2 7-6 (8-6) to earn a shot at second seed Francisco Cerundolo.