"I wouldn't say I'm confident," Crumpton said. "I'm hoping for a win but I'm always apprehensive before the start."
Crumpton (38) has won the title twice before, in 2000 and 2004, and is expected to add a third title this weekend.
Her main rival is Belinda Wimmer (Taranaki), who has yet to race under 35min. Crumpton's best time is the 33min 50sec she ran in 1999.
Winning is the main objective for Crumpton but she is also keen to break the New Zealand masters aged 35 to 39 record of 33min 58sec. It is held by former New Zealand representative Mary O'Connor (Canterbury).
The event usually attracts Australian runners, but this year it clashes with the Australian cross-country trials.
Crumpton's husband, Doug Crumpton, died of cancer in November, and subsequent training was disrupted because of a niggling injury.
She had only three weeks of training before winning the Otago women's 10,000m title in 34min 11.77sec last month.
"That was my last race and it gave me confidence," Crumpton said. "I have been running 130km a week consistently in training since then."
There is an added incentive for Crumpton to run a fast time at Inglewood because she is under consideration to make the New Zealand team for the world track and field championships at Berlin is August.
Her winning time in the Gold Coast marathon in July of 2hr 38min 21sec was 4min 30sec faster than the qualifying time set by the IAAF for the women's marathon.
Crumpton finished 33rd at the world championships in Helsinki in 2005 when she was the first of the three New Zealand women home, in a personal best time of 2hr 37min 03sec.
Tony Payne, the winner of the Otago championships in 32min 23.14sec, is a strong contender to win the junior men's title.
