An emotional Donna Vekic of Croatia in interviewed after defeating Lulu Sun of New Zealand in their quarterfinal at Wimbledon on Tuesday. Mosa’ab Elshamy/Associated Press

LONDON — Donna Vekic had thought a couple of times about quitting tennis, like when she struggled to get back to her best after knee surgery in 2021.

Now she’s happy she stuck with it.

The 28-year-old Croatian reached her first Grand Slam semifinal in her 43rd appearance at a major tournament by beating qualifier Lulu Sun 5-7, 6-4, 6-1 at Wimbledon on Tuesday.

“Those couple of years were very tough. I didn’t think I was ever going to come back to the level that I even had last year,” she said. “So this now, reaching my best result ever at a Slam, I’m really proud of myself, of the work that I’ve done, of the work that my team has done. I’m very thankful to them for believing in me when I didn’t.”

Jasmine Paolini of Italy reacts after winning a point against Emma Navarro of the United States during their quarterfinal match at Wimbledon on Tuesday. Alberto Pezzali/Associated Press

She will face No. 7 Jasmine Paolini for a spot in the final. Paolini beat No. 19 Emma Navarro 6-2, 6-1 to become the first Italian woman to reach the semifinals at Wimbledon.

“It’s so special. It’s a dream to be here in this position,” Paolini said in an on-court interview. “I was watching finals, when I was a kid, on this court. It’s strange to be here and to get the win and to be in the semifinal in Wimbledon. I feel so happy.”

Before the French Open this year, Vekic said she wanted to give up. She lacked energy and didn’t even want to practice.

“Now I’m in the semifinals. I think not just in tennis, in life things can turn pretty fast,” she said.

It’s only the second time a woman representing Croatia has reached the Wimbledon semifinals, after Mirjana Lucic in 1999.

The 23-year-old Sun, who played college tennis at the University of Texas, was making her debut at the grass-court tournament and is the first player from New Zealand to reach the Wimbledon quarterfinals in the Open era.

“I’ve had really great matches here at Wimbledon,” said Sun, who beat 2021 U.S. Open champion Emma Raducanu on Centre Court in the fourth round. “I think just energy from New Zealand fans and other fans, as well, is such a surreal moment for me that I definitely won’t forget.”

Sun said she struggled physically with cramping toward the end of the second set and in the third.

Serving for the second set at 5-3, Vekic committed five double-faults to help Sun break, but Vekic broke right back to force a deciding set, which the veteran player dominated.

“I was so angry at myself because even to get broken in the first set at 5-all, then finally managed to break her in the second set, then get broken. I don’t know where those double-faults came from,” Vekic said. “I wasn’t particularly nervous. I was surprised that I was just hitting double-faults.”