Top seed Maria Sharapova lost 6-2 ,6-4 to former world number one Justine Henin-Hardenne in the German Open quarter-finals on Friday.
Sharapova made a confident start, breaking Henin-Hardenne's opening service game, but the Belgian broke straight back and won the next six games.
The 18-year-old Russian would have become world number one if she had won the tournament.