High flying apprentice Beau Mertens has decided to knock back a Group One opportunity to continue his push for the Melbourne jockeys' premiership.

Mertens, 19, rode a winning treble at Flemington on Saturday to move within two wins of leader and defending titleholder Craig Williams.

On Monday he made the decision to pass up the ride on the Mick Price-trained Bassett in the Group One Goodwood in Adelaide on Saturday week.

Bassett was an unlucky sixth, beaten less than a length, in his Goodwood lead-up in Saturday's Group Three McKay Stakes at Morphettville won by Karacatis.

Mertens' manager Phillip Roost confirmed they had made the call to stay in Melbourne and ride at Flemington on Saturday week to chase the premiership.

The last apprentice to win a Melbourne jockeys' title was Nicholas Ryan in 2004/05.

Mertens, who took his season tally to 55 with his Flemington treble, is booked for seven rides at Sandown on Wednesday while Williams has six.

The in-demand apprentice also has a full book for Saturday's Caulfield meeting.