In 'catch me if you can tactics' under Jordan Childs, Just Fine ($21) held off a late bid from Point King ($5.50) by a head with Amade ($41) a short-half-head away third.
Just Fine is part-owned by My Racehorse who has owners in all parts of Australia and Waterhouse said it would be a great thrill for all the owners to have a Melbourne Cup runner.
"They're going to have a lot of fun running in our biggest race," Waterhouse said.
"What a wonderful thing. It happens nowhere else in the world, I can tell you, where people from all different walks of life can have a share in a horse for not much money and to be able to come here on the first Tuesday in November and maybe win a multi-million-dollar race."
Just Fine turned around his form with his success on Saturday.
The gelding ran a pleasing fifth in the Group 2 Chelmsford Stakes (1600m) at Randwick on September 7, but was comfortably beaten at his first Melbourne start for the campaign in the Group 3 MRC Foundation Cup (2000m) at Caulfield on September 21.
"I saw him the other day when he raced at Caulfield, I wasn't happy with him, so we gave him a little bit more work and just did some different things," Waterhouse said.
"I just knew today they would really have to try hard to beat him. It has been a matter of building, getting his fitness level right there, and he's got lovely cruising speed."
"And Jordan, that's Jordan at his best. When Jordan gets going on a front runner, he's very effective
