WTA Finals: Kiki Bertens reaches semi-finals after injured Naomi Osaka retires, Sloane Stephens also through

After losing the first set 6-3 to Kiki Bertens of the Netherlands, US Open champion Naomi Osaka, who had earlier gone off court for treatment, was in tears as she spoke to the tournament supervisor.
After losing the first set 6-3 to Kiki Bertens of the Netherlands, US Open champion Naomi Osaka, who had earlier gone off court for treatment, was in tears as she spoke to the tournament supervisor.ST PHOTOS: DESMOND WEE

SINGAPORE - Almost two hours after shedding tears of disappointment on the tennis court, Naomi Osaka made a room of more than 40 people laugh.

Asked during her media conference on Friday (Oct 26) if she felt relieved that her season was over, Osaka replied: "I'm sad I won't be able to see you guys."

Her breakthrough season, which saw her win her first Grand Slam title at the US Open, ended with a left hamstring injury that forced her to retire after she lost the first set 6-3 against Kiki Bertens of the Netherlands at the BNP Paribas WTA Finals Singapore presented by SC Global.

Bertens and Sloane Stephens qualified for Saturday's semi-finals, joining Elina Svitolina and Karolina Pliskova.

Osaka, who played with her left thigh taped, took a medical timeout while down 5-3 and left the court for treatment.

The 21-year-old Japanese was in tears as she made the decision to retire after the first set.

Acknowledging fans with a nod and a wave, Osaka was cheered and applauded by the crowd at the Indoor Stadium. She later told media she had hurt her left hamstring during her first match - a three-set loss to 2017 US Open champion Stephens - and that it got worse in her next two matches.

"There is this level of pain that I can play with, so I was definitely going to play," she said, adding that the pain became worse at 2-2 and she could not move.

"So I started trying to hit (winners) and then that wasn't working. Then I just felt like it was kind of pointless. I was just hurting myself more than helping."

Still, the world No. 4 managed a few smiles as she reflected on a "crazy year" in which she won the first two titles of her career.

"For me, it's just been a lot of new experiences - I'm very grateful that I was able to have the opportunities that I had," said Osaka, who won the Indian Well Masters in March.

"I feel like I have matured... At the beginning of the year, I was very uncertain with what I was doing. But now I feel a bit more calm."

Bertens, who beat Angelique Kerber and lost to Stephens in her earlier Red Group matches, said: "I think it was a solid match from the beginning for both of us, unfortunately she had to retire.

"It's never easy or nice to win a match like this, but it is what it is. I'll take it and I have some more recovery time for tomorrow."

The world No. 9 finished second in the Red Group as sixth-ranked Stephens topped the group after beating world No. 2 Kerber 6-3, 6-3 in the second match on Friday.

The American said: "I thought I stayed solid the whole time.

"I knew it was going to be a battle obviously, with a lot on the line. Angie is an amazing player, she's one of the best girls on Tour and one of the nicest players.

"So I knew it was going to be a battle and I just came out and played as hard as I could. I'm just really pleased to be through with the win."