Venus Williams was edged by Elena Vesnina in the BNP Paribas Open quarter-finals as Kristina Mladenovic also reached the last four.
Williams, a seven-time grand-slam champion, went down to fellow seed Vesnina 6-2 4-6 6-3 at Indian Wells on Thursday.
The American gave up an early break in the third set before falling 5-2 behind, and she saved three match points in the eighth game.
A lengthy ninth game followed as Williams squandered six break points before Vesnina completed her win.
And with a forehand winner, @EVesnina001 roars into her 1st SF in #IndianWells. She ousts Venus 6-2 4-6 6-3, sets up showdown w/ Mladenovic. pic.twitter.com/UT0qm6Cs8J
— BNP Paribas Open (@BNPPARIBASOPEN) March 17, 2017
MLADENOVIC UP NEXT
Awaiting Vesnina in the last four is Mladenovic, the Frenchwoman battling past Caroline Wozniacki 3-6 7-6 (7-4) 6-2.
Mladenovic, a title winner in St Petersburg and finalist in Acapulco already this year, continued her good form.
The 28th seed came from a set and a break down to get past 2011 champion Wozniacki, beating the Dane for the first time in four meetings.
Mladenovic moving on...
France's @KikiMladenovic notches 3-6 7-6(4) 6-2 win over former champ Wozniacki, advances to 1st #IndianWells SF. pic.twitter.com/BJK1L4xiuf
— BNP Paribas Open (@BNPPARIBASOPEN) March 16, 2017
She will need to do similar against Vesnina, who has won their only two previous matches.
Karolina Pliskova will face Svetlana Kuznetsova in the other semi-final at the WTA Premier event.