Maria Sharapova suffered her first defeat since returning from a 15-month doping ban to Kristina Mladenovic in the Porsche Grand Prix semi-finals.
Sharapova appeared to be heading to victory in Stuttgart after she raced through the first set in 35 minutes and broke in the second for a 2-0 lead.
However, French world No 19 Mladenovic produced a stunning comeback to secure a 3-6 7-5 6-4 victory in just over two hours, 38 minutes and a place in Sunday's final.
The Russian, who had not lost a set so far at the tournament, was playing in her first tournament since serving a ban for a positive test for meldonium at the 2016 Australian Open.
Victory in the semi-finals would have seen Sharapova return to the top 200 and secure entry into the qualifying tournament at the French Open without the need for a wildcard.
However, the five-time Grand Slam winner and two-time Roland Garros champion must now wait until May 16 to see whether she has been awarded a wildcard into the main draw for the Paris tournament.
"I'm not angry, I'd have loved to have used the opportunity when I was ahead in the second set, so I had a bit of a let down which allowed her to get back in the match, gain confidence and play well," said Sharapova.
"If at the start of the week I'd said I'd be in this position, I'd be pretty happy with that.
"The way I played, I was really happy with that. You are never sure what level you are going to come onto the court with, but I feel this is a great base with which I started here."
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