Top seed Caroline Garcia was humbled by American teenager Sofia Kenin in the quarterfinals of the Mallorca Open.
The 19-year-old recorded her first ever victory over a Top 10 player, by beating the world No. 6 in straight sets 6-3, 6-3.
Garcia -- the champion in Mallorca in 2016 and the favourite to take the crown again this year -- struggled on serve in the first set and was broken at 2-2 by the enterprising American.
In contrast Kenin never looked in trouble in the opening set on the grass in Spain, facing no break points and eventually winning it by breaking Garcia to make it 6-3.
The Frenchwoman responded well and finally broke through at the start of the second set before Kenin went up a gear to win five of the next six games.
She then survived a nervous final service game which included two double faults in a row to set up a semifinal against Tatjana Maria.
It was a less straightforward quarterfinal for the German who overcame seventh seed Lucie Safarova 7-6 (3), 4-6, 6-4.
In a marathon match lasting two hours and 35 minutes Safarova reproduced the aggression that saw her knock out Victoria Azarenka in the second round.
But Maria was stronger at the key moments, converting 5 of her 8 break points compared to 5 of 12 for Safarova, and moves into her first WTA semifinal in nine months.
Meanwhile Australian Sam Stosur maintained her record of not dropping a set in Mallorca this week as she battled past the USA's Alison Riske.
The American served eight double faults in total and failed to hold serve at all in the second set, handing Stosur a 6-4, 6-2 win.
She will play Anastasija Sevastova in the other semifinal after the Latvian third seed came back from a set down to beat Ajla Tomljanovic 3-6, 6-3, 6-1.