Former women's world No. 1 Ai Miyazato's decision to call time on her playing career at 31 years old was met with a mixture of shock and sadness from her fellow professionals on the LPGA Tour on Friday.

Speaking at the Volvik Championship, South Korea's former U.S Women's Open winner Choi Na Yeon said, "I'm really surprised. She was number one in the world and we grew up together. I feel really sad that I can't see her on the tour anymore."

Miyazato's compatriot Harukyo Nomura said, "I heard this morning and feel a little bit sad for her as she is only 31. She was always nice to me and I watched her play when I was an amateur I feel like she is the Pak Se Ri of Japan."

Norway's Suzann Pettersen said she had developed a special relationship with Miyazato and the Okinawa native's achievements in the game.

"Ai and I go a long way back and I have gotten to know her a lot. She became a good friend of mine and we have supported each other on and off the golf course for several reasons," said Pettersen.

"But if she leaves competitive golf on her own terms and is happy with that, then congratulations. You can't ask for much more and for what she has done for women's golf in Japan, or her achievements here, you have to take your hat off."

"I'll definitely miss her. She is probably the friendliest person out here on tour and she can leave the game knowing that she left the best of what she had."

Pettersen added, "She was world No. 1 and had I don't know how many wins, but a lot. Hopefully we can maintain a great friendship in the second part of our lives."

On Saturday in Japan local time Ai's brother Yusaku offered words of encouragement to his younger sister.

Speaking at the Japanese men's tour's Mizuno Open in Okayama Prefecture, Yusaku, 36, said, "To be honest it's a bit of a pity as I would have liked to see her play a little longer but it's her life and as a family member I want to support her decision."

Yusaku was first told directly about the decision during the New Year holiday period this year. He said that none of the members of the golfing family from Okinawa were disappointed and that they had praised her efforts.

"She was in a really cheerful mood and it sort of felt like she had been set free," he said. "I think she changed the golf world (in Japan) and I would like her to stay involved in the game."

Ai's management said Friday that she was calling it quits but no reason was given. A nine-time winner on the U.S. LPGA Tour, Ai will hold a press conference on Monday to speak about her decision.

Ai, who won 15 titles in the domestic tour, joined the LPGA Tour in 2006 and earned her first win in her fourth season at the 2009 Evian Masters in France, defeating Sophie Gustafson at the first hole of a sudden-death playoff.

In 2010, she won five tournaments on the LPGA Tour and rose to No. 1 world rankings, a position she would hold for 11 weeks during that season.

A hugely popular figure, who is fluent in English, Ai also paved the way for fellow Japanese, including Mika Miyazato (no relation), Momoko Ueda and Sakura Yokomine.

Her last victory on the LPGA Tour came at the NW Arkansas Championship in 2012. Her best finishes in major tournaments were third at the Women's PGA Championship (2006, 2010) and the Women's British Open (2009).

Miyazato's form has dipped in recent years and that has continued this season, with her best finish in five tournaments a 34th place. She is now ranked 115th in the world.