No.1 seed Jessica Pegula battled back from 4-0 down in the final set to outlast No.15 seed Irina-Camelia Begu 7-5, 4-6, 6-4 and make the Credit One Charleston Open quarterfinals on Thursday.

Pegula was in the Round of 16 in Charleston for the fourth time in her career, but she had never previously made it to the elite eight of the event. That all changed with her 2-hour and 30-minute win over Begu, although she had to survive many twists and turns to get there.

American No.1 Pegula will face No.12 seed Paula Badosa of Spain in the quarterfinals on Friday. Badosa moved into the Charleston quarterfinals for the third year running with a 6-1, 6-3 defeat of Diana Shnaider in 1 hour and 22 minutes.

Winning words from Pegula:

Topsy-turvy affair: After gritting out a tough first set, Pegula eased to a 4-0 lead in the second set, seemingly on her way to a comfortable victory over Romania's Begu.

But Begu suddenly showed off the form that brought her to three straight Charleston quarterfinals between 2015 and 2017, reeling off ten games in a row to steal the second set and take her own commanding 4-0 lead in the third set.

However, Pegula regrouped, breaking Begu at love twice in succession to pull back on serve. A drop shot winner gave Pegula her third love break of the set and a chance to serve out the match at 5-4. Pegula collected another love game to win her sixth straight game and complete the comeback.

Fast facts: With the come-from behind victory, Pegula leveled her head-to-head with Begu at 2-2. Begu won their first two meetings, but Pegula notched a victory en route to the Roland Garros quarterfinals last year.

World No.3 Pegula also denied Begu her first win over a Top 3 player. Begu has grabbed eight Top 10 wins in her career, but none over a player ranked better than No.4 at the time of their meeting.

Badosa books quarterfinal: Badosa reached the semifinals on her Charleston debut in 2021, and she backed that up with a quarterfinal run last year.

This week marks the first time she has posted three consecutive victories since the four-match winning streak with which she opened 2023 (across the United Cup and Adelaide 2).

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As in her previous round against Leylah Fernandez, the former World No.2 advanced by out-steadying and out-serving a younger opponent.

Competing in just her third WTA main draw, the 19-year-old Shnaider was slow out of the blocks, quickly falling behind a double break in a flurry of errors. But once she settled, the World No.95 drew frequent gasps from the crowd as she racked up 22 winners.

Highlights: Badosa def. Shnaider

Shnaider also garnered praise from her opponent afterwards.

"Crazy forehand, very powerful, and amazing future ahead," said an impressed Badosa in the on-court interview.

But Badosa delivered superior control, committing only 10 unforced errors to Shnaider's 19, and kept an iron grip on her service games thanks in part to five aces.

One of those sealed a key second-set hold for 3-2 after a trio of superb Shnaider forehand winners had threatened to shift momentum. Instead, Badosa was able to save both break points she faced in that game, along with the pair she had staved off in the first set.

In the final game, Badosa found her finest tennis of the day to close out victory, ending the best rally of the match with a fine drop shot winner.