Niwot has produced a well-timed run to deny Efficient in a thrilling Sydney Cup at Randwick.

Once given up as a racing prospect after a serious knee injury, Niwot sealed his comeback when he held off the 2007 Melbourne Cup winner in a desperate finish.

Niwot settled on the rail in the middle of the field before jockey Dwayne Dunn had the seven-year-old ready to challenge as the big field swung for home.

The veteran stayer looked set for an easy victory when joined the leaders at the 200-metre mark but he had to fight hard when Efficient loomed to his inside.

Victory ended a run of close calls in recent Group One races for Melbourne-based Dunn.

“When Efficient got up on the inside I said `no, don’t do it to me’,” Dunn said.

Niwot finished eighth in last year’s Melbourne Cup and he was given a weight-for-age build-up to Sydney’s 3200m marathon by trainer John Hawkes and his sons.

Hawkes, who prepared Cross Swords to win the 1994 Sydney Cup, has nursed Niwot back to top form after the gelding’s career looked finished in 2009.

“He’s come back from a smashed knee … he’s done a great job,” Dunn said.

“I had a great run in transit and he relaxed beautifully which is a great asset.”

The Gai Waterhouse-trained mare Once Were Wild finished third, just ahead of Nextanix.