Knight's Choice caused a huge upset when getting up in a thrilling finish to the Lexus Melbourne Cup under Irish-born jockey Robbie Dolan.

Trained by John Symons and Sheila Laxon, the five-year-old had finished fifth in the Bendigo Cup on his last start, but ran the race of his life to narrowly deny Japanese challenger Warp Speed by a short-head at odds of 90-1.

He provided the jockey, originally from County Kildare and who also starred as a singer on The Voice Australia two years ago, with the landmark success of his riding career on his Melbourne Cup debut.

An elated Dolan said: "Pinch me, I think I'm dreaming! It's incredible and I can't believe it. I watched the runnings of the Melbourne Cup over the last 40 years the other night and I thought my best chance was if I get him to stay the trip and he'll rattle home.

"He quickened up and he just proved everyone wrong. This is the biggest race in the world and I can't even put into words how much it means to win this."

Okita Soushi finished third, while Zardozi came home fourth in a race where the British and Irish raiders were out of luck. Absurde did the best of them when finishing an admirable fifth.

It was a second victory in the Flemington showpiece for Laxon, who previously created history when becoming the first female trainer to win the race that stops a nation with Ethereal in 2001.

It was a breakthrough Melbourne Cup triumph for joint-trainer Symons, who said: "What a thrill that was. You work with these horses 24 hours a day, seven days a week and you know where you've got them. We'd have been disappointed if he didn't run a good race. To run top five in a race like this you'd walk away happy, but to win it is a dream come true."

Laxon added: "What an amazing ride by Robbie. He always had faith in the horse – he studied the race so hard that we didn't give him instructions as he knew what to do. It brings it all back and I love that an Australian horse has done it. It's the people's Cup and that's what it's all about."

Vauban once again disappointed when finishing 11th under William Buick, with the Brian Ellison-trained Onesmoothoperator a further place back in 12th and Sea King finishing 14th for Harry Eustace. Buckaroo, sent off the 5-1 favourite, was ninth.