Top-seed David Nalbandian ground out a 7-6 4-6 6-3 victory over Italy's Fabio Fognini on Wednesday to reach the quarter-finals of the Buenos Aires Cup.
Nalbandian, ranked 11th in the world, took two hours and 18 minutes to dispose of his opponent on his home turf at the Buenos Aires Lawn Tennis Club.
"It was an extremely difficult game," Nalbandian told reporters.
"I managed to hold on for the tiebreak in the first set but lost my way in the second. I was able to pull myself together and break back in the third."
Nalbandian, who has not won a tournament on home soil in his four previous attempts, will face Potito Starace in his last eight match after the Italian beat Argentina's Juan Brzezicki 6-3 6-3.
Starace is returning to the circuit after serving a six week ban imposed by the ATP for a betting offence.
Fifth-seed Nicolas Almagro beat fellow Spaniard Oscar Hernandez 6-2 2-6 6-3 to progress. He admitted the heat had taken its toll.
"It was really hot out there and it looked like Oscar was really suffering too...now I want to rest and recover so I can start preparing for my next game," said Almagro, who won the Brazilan Open, his third title, on Sunday.
He will meet Juan Ignacio Chela in the quarter-final after the local player eased past Brazil's Thomaz Belluci 6-4 6-4.
The Buenos Aires Cup has already seen some upsets, with former winners, Argentine Juan Monaco and Spaniard Carlos Moya, exiting in the first round.