World number two Ons Jabeur failed in her bid to land the first ever WTA tournament to be held in her homeland Tunisia when she lost 6-3, 4-6, 6-4 to American Claire Liu in Monastir on Friday.
Top seed Jabeur went into the quarter-finals in irrepressible form having dropped just nine games in her previous two matches against the American Ann Li then the Russian Evgeniya Rodina, AFP reported.
But she was handed a surprise defeat by Liu, ranked 71 places below her, who came into the tournament in good form. The 22-year-old from California reached the quarter-finals in Tokyo in mid-September and was a finalist in Rabat in May.
Liu broke Jabeur's first service game and held on to that advantage to take the opening set.
The Tunisian favorite managed just 45 percent on her first serves but, in spite of further problems in the second, bounced back to level the match.
The errors continued in the third set - both players clocking 51 unforced errors in the match - with Liu edging the Wimbledon and US Open runner-up.
In the semi-finals, Liu will face Belgian Elise Mertens who needed two hours to wear down the 21-year-old Japanese player Moyuka Uchijima 6-0, 3-6, 6-4.
The other semi-final will pit Frenchwoman Alize Cornet against 12th ranked Russian Veronika Kudermetova.