Kim Smith's troublesome achilles tendon has forced her out of New Zealand's team to the world athletics championships in Moscow next month.
Smith qualified for the 10,000m after clocking 31min 46.37sec in April but her tendon troubles, coupled with a foot injury, have combined to restrict training in the last month.
The United States-based 31-year-old advised Athletics NZ high performance coach Steve Willis of her decision to withdraw on Friday.
She is looking to focus on rehabilitation and has targeted a return to racing in the United States autumn.
Smith will be hoping to find form in time for the Boston half-marathon on October 13, the third and final race in the Boston AA Distance Medley.
The medley is a lucrative three-race circuit which awards $NZ125,000 to the man and woman with the fastest cumulative time over 5km, 10km and half marathon.
Smith won the title last year, and is in prime position to take this year's event. She won the 5km race in April in 15min 16sec, then finished second over 10km in 33:34 last month.
She heads the women's leaderboard on a cumulative time of 48min 50sec, comfortably ahead of second-placed Millicent Kuria of Kenya on 50:01.