Former world number one Marcelo Rios, who is attempting to win an ATP tournament in his native Chile for the first time, reached the semi-finals of the Bellsouth Open on Friday.

Third-seeded Rios, whose last ATP title was in Hong Kong in 2001, beat Argentina's Agustin Calleri, the fifth seed, 6-4, 7-6 to reach the last four without dropping a set.

He will face either top-seed Gaston Gaudio of Argentina or Spain's Felix Mantilla in the semi-finals on Saturday.

"I'm still a little bit nervous but very determined," said the 27-year-old.

"I played well in parts, but I was a bit tired. Once I warmed up, I moved around better and I played the important points well."

Playing in his first tournament of the season, Rios appeared to be benefitting from a spell in Costa Rica recovering from the injuries which nagged him last year.

He also seems to have shrugged off the disappointment of Chile's Davis Cup defeat in Ecuador at the weekend when he lost one rubber and won the other, and an incident before, when he missed the plane to Quito after an all-night party at a beach resort.

Unseeded Spaniard David Sanchez joined Rios in the last four when he came from one set behind to defeat Italy's Andrea Gaudenzi.

Gaudenzi appeared to use up all his inspiration as the won a tiebreak 7-2 to take the first set. After that, Sanchez romped through the next two sets, dropping only three more games to complete a 6-7, 6-1, 6-2 quarter-final win.