Promising colt Dio D'Oro has finally got off the mark for trainer Gary Portelli and Darby Racing after mastering heavy ground for the first time at Randwick.

The two-year-old, who started his career by finishing runner-up to eventual Golden Slipper winner Estijaab, found a rain-affected track and a lower quality of opposition to his liking in the Spring On Sale Handicap (1100m).

Portelli had reservations about Dio D'Oro's capability on a wet track for his fourth career start, though a pedigree scan eased his anxiety.

"I found out today that his mother (Seeking Attention) was a mudder and his father (Medaglia D'Oro) was a mudder so it looks like we've got a mudder," he said on Saturday.

Dio D'Oro ($5) skipped under Rachel King clear to win by 2-1/4 lengths in front of King ($11), while God Of Thunder ($5.50) was a short half-head in third.

"He's come back in real good order. Obviously there was always a bit of a concern about the track first-up but we had two good trials," Portelli said.

"He ran second to Estijaab first-up in his last preparation. I don't think too many of these horses could do that."

Portelli had nothing specific planned for Dio D'Oro.

"We just want to win some races, put some prize money in the bank, get his confidence up and then we might end up in a good race," he said.