Japan's former Olympic marathon champion Naoko Takahashi left for the mountains of southwest China on Tuesday to begin her assault on next year's Beijing Games.

The 34-year-old has had mixed results since taking gold at the Sydney Games in 2000 and is anxious to begin preparations for Beijing early by seeking out a secret training camp in China.

Takahashi, whose shock failure to qualify for the 2004 Olympics in Athens plunged her future into serious doubt, will scour the mountains around Kunming for a high-altitude venue.

"I have never been to Kunming," Takahashi told reporters before leaving Japan. "I've decided to leave it late to qualify (for Japan's squad), so I'll have a good look."

Takahashi, who normally prepares for competition in the mountains of Colorado, is famous for her brutal training regime but she faces a battle even to make Japan's Olympic team.

Her absence in Athens was soon forgotten when fellow Japanese Mizuki Noguchi destroyed world record holder Paula Radcliffe of Britain on her way to winning marathon gold.

Takahashi was then well beaten by compatriot Reiko Tosa in Tokyo last November, but promised that it would not affect her preparations for Beijing.

Takahashi's sudden switch to China's mountainous Yunnan province -- where Noguchi also trains -- appears to underline her determination to end her career on a high in Beijing.

"It's near Japan and it's a place that's been yielding results," Takahashi said.

"I want to see it for myself and make it my own place."