Apprentice jockey Blaike McDougall has scored his first Saturday metropolitan winner, combining with in-form Signposted at Randwick.

Signposted took out the first race on Saturday, winning by 1-1/4 lengths from Dee I Cee with Oh So Splendido three-quarters of a length away third.

McDougall has now partnered Signposted to four consecutive wins for John Thompson, the Randwick trainer to whom he is indentured to.

"The horse is flying," McDougall said.

Thompson said McDougall had built a strong association with Signposted.

"He's level-headed and he's doing the hard yards at home," Thompson said.

"He's got a good set of hands on him and I think he'll go a long way."