Coco Gauff overtakes the injured Naomi Osaka in Beijing

Fourth seed Coco Gauff reached the quarterfinals of the China Open on Tuesday when Japan's Naomi Osaka withdrew before the third set in Beijing with a lower back injury.

Osaka won the first set 6-3 and led a break 4-3 in the second set before losing the final three games and promptly resigning.

“I’m sorry,” Gauff said to Osaka after hugging in midfield. “It’s great to have you back.”

Gauff, who took a 3-2 lead in their head-to-head series, helped the four-time Grand Slam champion carry her bags off the court.

“I wasn't sure if it was her hip or her back. “I just knew she could barely bounce on her serve toward the end,” Gauff said, “so I knew it was something that was probably bad in the moment,” but hopefully it's something that isn't a long-term thing. “

Gauff said she was surprised the game ended so abruptly.

“Towards the end of the second set I really noticed it was really limiting her movement,” Gauff said. “Even if you saw the last point, I was just trying to keep the ball in because I knew what was going on. But honestly, I didn’t expect her to give up at that moment.”

Gauff balanced six aces with six double faults and saved only one of six break points in the 88-minute game. She will face Ukrainian qualifier Yuliia Starodubtseva for a place in the semifinals of the WTA 1000 event. Starodubtseva defeated No. 10 seed Anna Kalinskaya of Russia 7-5, 6-0.

Spaniard No. 15 seed Paula Badosa defeated No. 2 seed Jessica Pegula 6-4, 6-0 in just 64 minutes, her first win in four meetings with the 2024 US Open finalist.

Badosa trailed 3-1 in the opening set but then won 11 of the last 12 games, including eight in a row, to close out the match.

“She's one of the players I never want to play against – she's very solid, hits very flat, changes direction very well, so I knew it would be difficult,” Badosa said after the game. “Yesterday I was preparing for a fight, but I think everything went pretty well today.”

“I moved well, my backhand, my forehand were there today and I fought. Every point was very important for me, especially against Jessica because she can come back at any time; I'm really happy with this win, to be honest.”

Badosa's quarterfinal opponent will be China's Shuai Zhang, who won 6-4, 6-2 against No. 23 seed Magdalena Frech of Poland. Zhang converted six of twelve break chances and has yet to lose a set in the tournament.

–Field level media