Mirjana Lucic-Baroni of Croatia bucked an upset trend that claimed Caroline Wozniacki on Friday, ending the hopes of hometown favorite Shelby Rogers at the WTA event in Charleston, South Carolina.
Croatia's Lucic-Baroni, seeded 11th, defeated Rogers 6-7 (7/9), 6-1, 6-1 to book a semi-final berth.
She was the only seeded quarter-finalist to advance as fifth-seeded Wozniacki, eighth-seeded Anastasija Sevastova and 10th-seeded Irina Camelia Begu were all toppled by unseeded players.
Lucic-Baroni, 35, is the oldest player remaining in the tournament. When she played in Charleston for the first time in 2001, Rogers was a ball girl in the event.
"It was beautiful in a way," Lucic-Baroni said. "It was difficult playing against the crowd, because Shelby is from here. It's normal. It's always tough, but I felt they were very respectful. They were cheering for their home girl, and it's totally normal.
"The wind was what was really difficult today. It was incredibly hard, and the fact that I came out yesterday and today playing some great tennis and winning in these conditions, it's incredible, really, really good effort.
"I would rather play with a live lion running around in normal conditions than play in today's weather."
Lucic-Baroni had a set point while serving at 5-4 in the first set, and she had another set point at 6-5 in the tiebreaker, but Rodgers eventually captured the first set on her second opportunity.
After the split the first two games of the second set, the Croatian veteran seized command, winning 10 straight games.
"I thought we had a very good level," Rogers said. "It was super entertaining. And bad luck, I wish I could have kept it up."
Wozniacki, a former world number one who would have moved back into the top 10 in the rankings by reaching the semis, fell 6-2, 6-4 to 19-year-old Jelena Ostapenko of Latvia.
Wozniacki led the first set 2-1, before the 66th-ranked Ostapenko reeled off five straight games to pocket the set.
Wozniacki fought off a match point on her own serve at 3-5 of the second, but Ostapenko closed it out in the next game on her fourth opportunity.
In other quarter-final matches, 19-year-old Daria Kasatkina of Russia upset Romania's Begu 6-4, 6-1, and Laura Siegmund of Germany beat Latvia's Sevastova 6-2, 6-4.