World number four Jelena Jankovic fought back from a set down to beat Italy's Roberta Vinci 3-6, 6-3, 7-6 in the quarter-finals of the Andalucia Tennis Championships on Friday.
The Serbian second seed, by far the highest-ranked player left in the tournament after Wednesday's shock exit of world number one Serena Williams, found it tough going against the 67th-ranked Vinci on the clay in Marbella.
Both players struggled to hold serve in the blustery conditions and Vinci saved three match points in the 10th game of the third set and another in the tiebreak before Jankovic sealed the win at the fifth attempt, taking the tiebreak 8-6.
She will play Anabel Medina Garrigues on Saturday for a place in Sunday's final after the Spanish fourth seed beat sixth-seeded Italian Sara Errani 6-2, 6-7, 7-5 in their quarter-final earlier on Friday.
"I'm feeling really happy as it was really a tough match," Jankovic said.
"She played really great and she was mixing up the game with a lot of slices and drop shots. It took me a while to get into the match, especially in the windy conditions.
"I was able to stay strong and play point by point and fight really hard until the end and I managed to do it."
The other semi-final will feature Spain's Carla Suarez Navarro, who trounced Williams' conqueror Klara Zakopalova of the Czech Republic 6-1, 6-2 and Romania's Sorana Cirstea, who came through 6-4, 2-6, 7-5 against Kaia Kanepi of Estonia.
Injury-hampered Williams lost 6-4, 3-6, 6-1 to Zakopalova in the first round on Wednesday.
The top-seeded American had not recovered from a thigh problem that affected her performance in Miami last week and she was broken seven times by the 95th ranked Czech.
Williams will be replaced at the top of the world rankings by Russian Dinara Safina when they are updated on Monday.