China's Xue Bai crosses the finish line to win gold in the women's marathon on Sunday. ((Herbert Knosowski/Associated Press))

Survival was the order of the day in the women's marathon at the world track and field championships in Berlin on Sunday.

The oppressive heat took its toll on many of the top athletes, resulting in a relatively slow winning time in the 42.195-kilometre race through the downtown.

Xue Bai of China dropped Japan's Yoshima Ozaka and Aselefech Mergia of Ethiopia in the last three kilometres to win the gold medal and the accompanying $60,000 US first-place prize. Her time was two hours, 25 minutes, 15 seconds.

Ozaka took silver in 2:25:25, with Mergia fairly staggering across the line for the bronze in 2:25:32.

Chunxiu Zhou and Xiaolin Zhu of China finished fourth and fifth to give China victory in the World Cup team competition. Japan took second and Russia was third. The Ethiopians were fourth while Kenya's team managed just a sixth-place finish. The top Kenyan was Julia Muraga, in 12th place

Canada's sole representative, Tara Quinn-Smith, started cautiously. She reached the halfway point in 1:15:29 before slowing considerably over the second half of the course. She crossed the line in 36th place with a time of 2:39:18.

"I was going for the experience. This was my first championship and my second marathon ever," the 29-year-old Waterdown, Ont., native said. "It was around 23 km where I started feeling it. I had to work. My legs were a bit heavy so I slowed down considerably.

"I am happy that I held it together and finished relatively strong the second half. It was definitely a good experience knowing that I can tough it out and next time try to hang in a bit longer and tough it out longer."

Medics kept busy

Medics and physiotherapists were kept extremely busy as runners struggled to stay on their feet at the finish. Amazingly, only 2:33 separated Bai and 10th place Kara Goucher of the United States.

Quinn-Smith had a good look at the course a day earlier as her husband, Andrew Smith, finished 53rd in the men's race.

"It was good seeing what the guys went through the day before," she admitted. "I had an idea then of what the course was like in general. By the hotel there was a spot I kind of popped in and out and could cheer but also stay off my legs."

"I stuck with my race plan and thought, 'You know what? Regardless of the heat, I am going to stick with it, go hard and go after it.'"

The victorious Xue seemed genuinely pleased to be a member of her country's victorious World Cup marathon team.

"I ran last year in Beiing. After that I wasn't in very good shape," she said. "Early this year I started training hard and before this competition I was in good shape. I am happy to win but I am also lucky because a lot of the top runners were not here today. I have to do a lot to catch up to them."

Among the absentees Sunday were world record holder and 2005 champion Paula Radcliffe and 2009 London marathon champ Irina Mikitenko of Germany.

"It is important for me, and also for my teammates and coach, to win this IAAF World Cup team competition because we missed it last time in Osaka by only a few seconds," Xue said. "This is very, very important. I am happy that I am personally world champion and also World Cup champion."