It was not always plain sailing as both a coach and father, but Masaru Miyazato is happy and proud of his daughter Ai who confirmed on Monday she will finish her career at the end of the season.

The former world No. 1 swung her first club under the tutelage of Masaru when she was four years old, and won a pro tournament at the age of 18 in 2003 as a high-school student -- before her either of her elder brothers and fellow professional golfers, Yusaku and Kiyoshi, had claimed any silverware.

"She was an unruly girl, and having a coach-player relationship while being a father and child is really difficult," said Masaru after his daughter's emotional press conference in Tokyo. "But she heard me when it really mattered."

"We did argue a lot, there was a time when I was telling her the right thing and she didn't do it. But we walked this path together both through the tough and good times. I think it's been an excellent career."

Masaru said there was no surprise when he heard of her decision ahead of this season, and believes she is making the right choice.

"Technically she can still go far, but I don't think it's a good thing to continue as a golfer if her motivation is not there."

"Yes she's making the cut at tournaments and managing to make a living out of it, but that's not what is demanded of Ai. What Ai is tasked with is to move people emotionally through the sport, while maintaining her strong motivation and competitiveness. If her will is fading, then it's the right time to call it quits," he said.

Masaru thought his daughter was in for a rough ride when she played her first U.S. LPGA Tour event at Hawaii's Turtle Bay in 2006.

"I expected things to be tough when I saw how high the level was on the U.S. tour," he said. "Ai was a sailboat sailing off into the ocean and there were some massive waves waiting for her. She was heading into that environment and I couldn't really imagine her ever anchoring at No. 1."

There was one thing that put her above the rest, on which Masaru believes Ai's career always hinged.

"Her putting was better than others. She had approach play too and she could cut it once on the green," he said. "Ai's style was to hit the green even if she was yards behind (the long) drivers. That clicked and got her to the top of the world. Once that went downhill the whole thing became difficult."

Ai, who remained her cheerful self through most of the 45-minute press conference before tears welled in the final moments, had only words of gratitude for her mentor.

"He taught me to be a human being before a golfer," Ai said. "He understood who I am, not always obedient, and we could share lots of memories. I'm one fortunate golfer."

Ai said she does not know what the next chapter of life will hold, but Masaru already has a plan.

"We've traveled across the U.S. but always to a golf course, so I want her to take me around the States," Masaru said. "She'll finally be doing her daughterly duty."