Jockey Jim Byrne could offer no excuses after long odds-on favourite Our Boy Nicholas ran last at Doomben on Saturday.

Our Boy Nicholas ($1.65) had won his only three starts in Queensland but was under pressure from the 600m and finished last, five lengths from the all-the-way winner Bush Aviator ($6).

Stewards questioned Byrne after the race and he told them he had hoped to sit outside Bush Aviator but he had been unable to cross Itchintowin who was running second.

Byrne said he had then elected to drop back to second last but the pace of the race slowed.

He said when the winner sprinted at the 600m, Our Boy Nicholas had held his ground but been unable to pick up.

The race gave apprentice Luke Tarrant his 13th city winner this season and he has opened a big lead in the jockeys' premiership.

"We planned to lead and then slow up. The race worked out perfectly and he gave me a good kick on the corner," Tarrant said.

Bush Aviator won a Listed race in Hobart at his first race start for trainer Danny O'Brien but struggled in Melbourne before his transfer to Tony Gollan at Eagle Farm last year.

Gollan was in Melbourne on Saturday but foreman John Fleming said Bush Aviator was honest and would chase similar races.