French No.1 Marion Bartoli bowed out in the quarter-finals of the Paris Open on Friday with a 7-6 (9-7) 6-4 defeat to Germany's Mona Barthel.
Bartoli was aiming to cap her recall to the Fed Cup team this week after a nine-year exile with a maiden triumph in the French capital, but the world No.10 came up short as she faltered badly at key moments.
The third seed, runner-up in last year's tournament, led 6-2 in the first-set tie-break but squandered four set points as Barthel, ranked 45th, escaped from a perilous position to move in front.
The German then secured an early break that proved decisive in the second set with Bartoli unable to offer any resistance to Barthel's serve.
"It was a difficult battle. The match was very hard physically. The first was very tough, she played extremely well. I thought it was a match with lots of intensity," said Bartoli.
Barthel will now face French teenager Kristina Mladenovic in the semi-finals after the 19-year-old stunned world No.8 Petra Kvitova 6-3 6-4.
Mladenovic, who was included alongside Bartoli in France's Fed Cup team for next week's clash with Germany, capitalised on three service breaks to take the first set and kept her foot on the throttle in the second to send Kvitova crashing out.
Italian top seed Sara Errani avenged her defeat to Carla Suarez Navarro at last month's Australian Open, as she edged past the Spaniard to reach the last four.
World No.7 Errani was a first-round casualty in Melbourne following a straight sets loss to Suarez Navarro, but the Italian demonstrated her typical craft and determination to earn a gruelling 7-5 4-6 7-5 win in just over three hours.
Dutch player Kiki Bertens followed up her second-round win over Dominika Cibulkova - her first triumph over a top 20 opponent - by casting aside 18th-ranked Lucie Safarova 6-1 7-5.
The 21-year-old, who made the main draw as a lucky loser following the illness-enforced withdrawal of Czech Lucie Hradecka, broke sixth seed Safarova three times as she cruised through the opening set.
Bertens then again broke her Czech opponent early in the second set to seize the initiative before Safarova recovered to level at 4-4.
But a loose service game at 5-5 from Safarova presented Bertens with the opportunity to serve for a place in the semis and she took full advantage, closing it out with an ace on her first match point.
"It's been an amazing week. My tennis is going very well, I'm very happy with that," said a smiling Bertens.
"I think I played well. I was concentrated from the first point and I think that was a good thing.
"I'm playing very good and I hope that can continue tomorrow," added the world number 65, who will face Errani for a place in Sunday's final.