David Ferrer will defend his Copa Claro title in the final against Stanislas Wawrinka of Switzerland after their straight-sets wins.
Ferrer defeated fellow Spaniard Tommy Robredo 6-3, 6-2 on the outdoor clay, and Wawrinka defeated Nicolas Almagro - also of Spain - 6-3, 7-5 to reach his first final in the Argentine capital. He lost his two other semi-final appearances, including last year to Almagro.
Ferrer is the heavy favourite to take the title again after improving his record against Robredo to 6-2.
"It was a tough match physically," said Ferrer, who has played three straight days and will make it four in the final. "Maybe it was my best match of the week."
Robredo, who won this tournament four years ago, broke Ferrer in the first game, and momentarily it looked like an upset might be brewing. But Ferrer's reply was to break Robredo twice to make it 5-3.
Ferrer broke again in the third game of the second set, capitalizing on Robredo's rush to go for winning shots and his own ability to return almost everything that Robredo put in play.
"I started slowly," Ferrer said. "I was a bit nervous and Tommy was right in the groove."
Ferrer won in Auckland, New Zealand, last month and will be going for his 20th career title.
Wawrinka broke Almagro in the 11th game of the second set and won when Almagro retuned his serve wide.
"He's always tough," Wawrinka said. "Nico is a great champion."
Wawrinka lost to Almagro last year in the semifinals, but delivered this time to put himself in position on Sunday to win his fourth ATP title.
"Last year he beat me here. Today I was a little bit better," Wawrinka said. "I was playing a bit more aggressive and that was the key."
Attendance has been hurt at the event by rainy weather the first few days, and later by the failure of any Argentines to get past the quarterfinals.