Trainer Brian Smith's theory about the new Eagle Farm surface being a track for fit horses was proven with Shuda Known Better's win.
Shuda Known Better ($9.50) came from second last at the 600m to run down the leader Social Vampire ($4.20) by 1-1/4 lengths with a length to Son Of A Brut ($13) in third place.
She ran 1 minute 26.65 seconds for the 1400m which was reflective of the heavy track rating.
Shuda Known Better was stepping up from 1110m but handled the distance rise with aplomb.
Smith said Shuda Known Better was rock-hard fit after having three lead-in runs.
"There is no doubt the new Eagle Farm is a track for hard and fit horses. It is a long way down that straight," he said.
Jockey Andrew Spinks continued his good run for Smith with the winning ride.
"Andrew has been a great help to me in recent months and I am glad the owners let me keep him on. He has been telling me the filly needed 1400 metres and he was right," Smith said.
"Shuda Known Better as been known as a speedy thing but I have always thought she will make a nice staying type."
Listed - East Cape Guineas
G3 - Kings Cup
G2 - Resource Recycling Superstars Championship
G3 - Lamb & Hayward 4&5yo Trotting Championship
G2 - Storer Motors Nz Trotting Oaks