Top seed Tomas Berdych toughed out a battling 3-6, 6-4, 6-4 win over qualifier Leonardo Mayer while second seed Milos Raonic was eliminated from his quarter-final at the ATP-WTA Portugal Open on Friday.
Berdych, who only took a wild card to get more clay matches with the French Open just three weeks away, almost found himself on the sidelines as he dropped the first set to his 88th-ranked Argentine opponent.
The sixth-ranked Czech survived a roller-coaster final set and will Saturday face Romania's Victor Hanescu who beat home hope Gastao Elias 6-1, 7-5.
"I have to be ready for tough battles like this," said Berdych. "He hit the ball hard and played well at times, but he was also up and down.
"I bought my best tennis in the last three or four games and got through, that was the most important thing today. I need to find a better rhythm on clay."
Raonic again disappointed on clay, bundled out in just under 90 minutes 7-5, 6-4 by Argentine Carlos Berlocq.
The Canadian was limited to six aces and the same number of double-faults in defeat as he lost serve four times.
"At the end of the day, I want to do much better this season on clay than I have in the past," he said. "I'm putting a lot of attention on Madrid (next week) and Paris (French Open).
"On clay, training doesn't mean a lot. You need confidence that only comes through wins."
Number 62 ranked Berlocq next plays 98th-ranked Daniel Gimeno-Traver, after the Spaniard upset third-seeded compatriot Marcel Granollers 6-1, 6-2.
- Kuznetsova ends three-year wait -
In the women's event Svetlana Kuznetsova reached her first final in more than three years with a 6-3, 6-1 win over fellow Russian Elena Vesnina to set up a clash with Carla Suarez Navarro.
The Russian seventh-seed, who owns Grand Slam titles from 2004 in Paris and 2009 in New York, will take on the Spanish top seed competing in her third straight final in Portugal but without a career trophy of any kind.
Suarez Navarro overcame Romanian qualifier Irina Begu 7-6 (7/3), 6-1 in one and three-quarter hours.
"I've been playing well the last two weeks, and I'm happy to be in the final. I never really expected this, especially on clay," said Kuznetsova, whose last clay final was at Roland Garros five years ago.
"This means a lot to me. I'm far from my top level but my tennis can still get me into this final. I have a chance to beat a lot of top players and I'm gaining confidence."
Suarez Navarro, who cruised through her early rounds with barely a challenge, was made to work in the semi-final by Begu, ranked 117.
The challenger kept the first set competitive before getting discouraged over line calls and fading in the second.
As a result of her success, Suarez Navarro became the season singles win leader with 25 victories.
"I'm feeling good on the court and I'm very comfortable here. I want to go out and play my best tennis in the final and we will see what happens," said the Spaniard.
The 28-year-old Kuznetsova last played a final in February, 2011 in Dubai, where she lost to Caroline Wozniacki. The Russian's last trophy was earned at 2010 San Diego.
She began last year ranked 71 and has now fought back to 29th on the WTA list.