Trainer Gary Duncan's gamble to turn his handy sprinter Magnufighter into a stayer paid off when the gelding won the Singapore Turf Club Trophy at Doomben.

As a younger horse, Magnufighter raced in some top races over shorter trips but Duncan has always believed that middle-distance racing would be his forte.

Magnufighter ($8) proved Duncan was correct when he beat Chillin With Dylan ($41) by three-quarters of a length with a head to Deconstructed ($10) in third.

Duncan said before this campaign he had come up with a plan for Magnufighter and he had stuck to it.

"I think the Magic Millions Trophy (over 2200m on January 12) will be ideal for him. I could have run him in the 1600m race today but in the end we decided to go with the longer one," Duncan said.

"He should make the field this year after that win and we will have to find another race for him before Millions day."