China Open: Coco Gauff reaches quarterfinals after injured Naomi Osaka ends her career, Paula Badosa flattens Jessica Pegula

Coco Gauff reached the quarter-finals of the China Open after Naomi Osaka was forced to withdraw from their blockbuster clash in Beijing as the match ended in a draw in Beijing.

Osaka led by a set and a break before fourth-seeded Gauff fought back to level the score at 3-6, 6-4 and force a decider.

However, the former world No. 1 was unable to continue and her American opponent helped her carry her luggage off the court after 87 intense minutes of competition.

Osaka's withdrawal sent Gauff into the last eight for the second consecutive year, where she will face Ukrainian qualifier Yuliia Starodubtseva.

“It was a good game up until that point. I wish Naomi a speedy recovery, nobody wants to win a match like that, especially not in one set,” Gauff said on court.

“I did my best, it wasn't my best tennis. It was one of those games where you give your best with every point.

“It’s cool to be in the quarterfinals again here in Beijing. I've been playing the late game every day, so maybe I'll get some sunshine in the next game. We’ll see what the schedule allows.”

Osaka's withdrawal was an unfortunate end to an otherwise exciting encounter.

After an early break exchange, Osaka began to pull away, beating off most of the fast-paced rallies on the baseline and securing the break 3-1 with a brilliant drop volley into the expansive court. But Gauff broke out again, restoring the score at 3-3 as a first-class set of brutal power hitting unfolded.

Osaka briefly had a medic on court after the fifth game and her back appeared to be causing her problems at times as she moved cautiously in transition, but she continued to put pressure on Gauff, who in turn had chances for a break.

A double fault in the eighth game gave Osaka two break points and the four-time major winner was in control on the baseline, moving Gauff from side to side and forcing her to the net.

Osaka looked cool and composed as she served the set 5-3. Both players hit fast, hard shots and Gauff struggled to stay with it, but she exaggerated a return and conceded the set in the 36th minute.

Gauff's resolve was dashed as she went down a set, got back to 15 with a businesslike serve and took a 2-0 lead after a game in which she showed the best of both players.

The quality rallies along the baseline continued and both players mixed up their game, with Gauff beating the touchline with a brilliant backhand winner and delicately playing a gentle drop shot as Osaka was stuck at the back of the court. Despite skillfully targeting Gauff's vulnerable forehand wing, Osaka netted to score an early break and continued to look physically uncomfortable.

But as in the first set, the breaks continued and both players fought in two mammoth games. Gauff had seven points in both games but couldn't convert a single one as Osaka leveled at 2-2, and at 3-3 the momentum turned again when Gauff suffered a poor service game full of double faults to make it 4-3 fell behind.

The drama didn't stop there: a first double fault from Osaka on break point equalized again and set Gauff on the way to a run of three consecutive games that concluded the second set.

Gauff's next opponent, world number 115 Starodubtseva, continued her excellent week by defeating number 10 seed Anna Kalinskaya 7-5, 6-0.

The winner of their duel will face Paula Badosa or Shuai Zhang in the semi-finals in Beijing.

Badosa defeated US Open runner-up Jessica Pegula 6-4, 6-0 to reach the last eight, while home favorite Zhang defeated Magdalena Frech 6-4, 6-2.

The Spaniard's ferocious performance meant her victory was secured in just 64 minutes after she recovered from a 3-1 deficit in the first set and won 11 of the following 12 games.

“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.

“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. To be honest, I'm really happy with this win.”