* Jockey Oliver wins redemption after betting scandal
* Trainer Waterhouse celebrates breakthrough after 20 years (Adds new quotes, details)
By Ian Ransom
MELBOURNE, Nov 5 (Reuters) - Favourite Fiorente prevailed in a furious sprint down the final stretch to win the A$6 million ($5.70 million) Melbourne Cup on Tuesday and deliver sweet redemption for controversial jockey Damien Oliver.
Fiorente, runner-up to Green Moon last year, enjoyed a textbook ride in the gruelling two-mile handicap from three-time winner Oliver, who a year ago was embroiled in scandal amid an illegal betting probe.
Oliver coaxed the six-year-old stallion to the front in the final 100 metres to beat British stayer Red Cadeaux by three-quarters of a length with Mount Athos finishing third.
The win in the 153rd running of the Cup, one of the world's richest races, was especially satisfying for 41-year-old Oliver, who only returned to the saddle in September after serving a 10-month ban for betting on a rival horse in 2010.
His presence in last year's race aboard Americain provoked much debate as news of his complicity in the illegal betting scandal swirled in the lead-up.
Oliver was backed by Sydney-based trainer Gai Waterhouse on his return and he rewarded the grand dame of Australian racing with her first Melbourne Cup.
In addition to last year's heartbreak, Waterhouse also tasted the disappointment of runner-up finishes with Te Akau Nick in 1993 and Nothin Leica Dane in 1995.
"Gai was one of the first people to get behind me when I came back," an emotional Oliver, who rode 1995 winner Doriemus and Media Puzzle in 2002, said trackside.
"There's a lot of emotion going through my body right now."
Waterhouse hailed Oliver's ride which saw Irish import Fiorente, carrying 55 kg from barrier five and backed into 6-1, edge ahead of the Ed Dunlop-trained Red Cadeaux in front of a heaving crowd of more than 100,000.
"Didn't he ride him a treat?" a glowing Waterhouse, wearing a necklace of huge pearls and a teal-coloured dress and hat, said trackside.
"I think (backing Oliver) was the crux. I think it was what won us the Cup," the 59-year-old later told reporters.
Scotland-born Waterhouse, whose late father Tommy Smith won two Melbourne Cups and remains an icon of Australian racing, ended 20 years of frustration to win Australia's most coveted racing trophy.
"It ticks the best bucket-list ... It's a burning desire (to win it)," said Waterhouse, who became only the second female trainer to win the Cup after the New Zealand-based Sheila Laxon's 2001 triumph with Ethereal.
"I could see he was picking up before the turn ... Then the last 200 metres I knew he had it won."
Starting on barrier 23 in the 24-horse field, eight-year-old gelding Red Cadeaux was equal third-top weight with 56.5 kg and rated a 60-1 chance in a third tilt for the Cup.
That he ran another gallant race will be little consolation to trainer Dunlop, who also missed out on a first Melbourne Cup for Britain when the same horse was beaten in a photo finish by French stayer Dunaden in 2011.
The Luca Cumani-prepared Mount Athos came in third on Tuesday, leaving the Newmarket-based trainer still chasing the trophy after eight attempts.
Dubbed "the race that stops a nation", the Melbourne Cup has long shed its image as a showcase of Australian breeding, with only five of the field of 24 horses bred locally.
The race's soaring prizemoney has also lured foreign trainers to spend small fortunes in bringing horses Down Under, and five from outside Australia and New Zealand have won the Cup since Irish trainer Dermot Weld's breakthrough with Vintage Crop in 1993.
Five of the nine foreign raiders in Tuesday's field finished in the top eight, with Simenon, trained by Irishman William Mullins, placing fourth and Marco Botti-trained Dandino fifth.
Australian property magnate Lloyd Williams was widely tipped to win a fifth Melbourne Cup as an owner of six horses in the field but was left disappointed as Fawkner was the pick of the bunch finishing sixth.
Tuesday's race had threatened to spiral into controversy when stewards probed race-day treatments to Dunaden and Waterhouse-trained Tres Blue.
Dunaden was treated for an ulcer while Tres Blue had treatment for an irritated hoof. The horses were cleared to race but stewards will hold an inquiry later into both their stables later this week.
The Cup ended on a sour note with French stayer Verema having to be destroyed after the five-year-old mare broke a leg and failed to finish. ($1 = 1.0530 Australian dollars) (Editing by Peter Rutherford)