Walker finishes fifth in monobob

Australia's Bree Walker reacts after her final run in the women's monobob bobsleigh. FRANCOIS-XAVIER MARIT/AFP via Getty Images

Bree Walker has fallen agonisingly short of another Olympic sliding medal for Australia, finishing fifth in the women's monobob in Beijing.

Hot on the heels of Jackie Narracott's historic silver medal in the skeleton, Walker was unable to catch the top three in the final run at Yanqing Sliding Centre on Monday.

Kaillie Humphries, who won two gold and a bronze competing in the two-woman bobsleigh for Canada before switching her allegiance to the United States, added another to her collection with an emphatic victory.

It's the first time monobob has been included on the Olympic program.

Walker, a former 400m hurdler, started the day in seventh spot after two runs on Sunday and jumped into fifth after banking the second quickest run of the morning behind Humphries, thumping the slide of her sled in delight in after crossing the finish line.

She needed to make up another 0.55 seconds to move into the bronze-medal position but ultimately fell short.

The 29-year-old Victorian laid down a final run of one minute 5.21 seconds for a combined time of 4:21.46.

With the medals awarded on the cumulative time after four runs, Humphries' last was the slowest of her efforts with a 1:05.3 but she still managed a combined time of 4:19.27.

She finished well clear of fellow American, World Cup champion Elana Meyers Taylor (4:20.81), with Canadian Christine de Bruin (4:21.03) taking the bronze medal.