Golf-New Zealand's Ko balancing fatigue with Grand Slam ambition

Feb 25 (Reuters) - Three-times major champion Lydia Ko says the pursuit of golf's rarest prizes is still enough to stir her competitive fire, even as her 13 years in the LPGA weigh more heavily on her body.

The 28-year-old New Zealander returns to this week's HSBC Women's World Championship in Singapore as defending champion, buoyed by a pair of top-five finishes in Thailand and the Tournament of Champions in Florida to open the season.

The former world number one has won a full set of Olympic medals and three majors among her 23 LPGA Tour titles but would like either a first Women's PGA Championship or a maiden U.S. Women's Open crown to complete the career Grand Slam.

The LPGA considers women who have won four of the tour's five majors to be career Grand Slam winners.

"There might be the question in your head like, 'OK, what’s next?' And I’ve had that question in my career at multiple points, and even after winning the silver medal in Rio, that was such a big goal of mine," Paris Olympics champion Ko said in Singapore.

"After that was done, I had lost a little bit of sense of direction in my career.

"I think the U.S. Women’s Open has always been a big star or key on the schedule in any season. I obviously haven’t won that. So that’s always a motivation."

Though Ko took the world by storm as a 17-year-old world number one in 2015, she has often spoken of quitting the game at 30 to follow other pursuits rather than grinding on the tour into middle age.

She said she was no longer as resilient physically as before.

"To be honest, now that I've been on tour for so long, my body, I know, is not the same as 10 years ago," she added.

"So my recovery is not as fast as I think it should be.

"Sometimes I think the fatigue catches up to me more than where I am mentally.

"So, I’m just trying to have a good balance of that."