Trainer David Vandyke is looking to give his client and friend Sam Mayer a double for the week when Emerald City runs at Doomben.

Mayer is the part-owner of Invincible Express who won at Ipswich on Wednesday, and Emerald City who tackles Saturday's Mandate Open (2200m).

Vandyke had been keen to win the Toowoomba Cup two weeks ago with Emerald City but things didn't go to plan.

"Emerald City is no good on wet tracks and the rain beat us. He had to go into the Toowoomba Cup with just one run under his belt," Vandyke said.

Emerald City did a good job under the circumstances as he was caught deep most of the race but still finished sixth to Cylinder Beach.

Vandyke was able to win four metropolitan staying races in a row with Emerald City in Brisbane late last year.

The gelding, who has won eight races in total, was once considered a possible stakes stayer and Vandyke will map out a possible winter carnival campaign after Saturday's race.

Michael Cahill, who won on Invincible Express on Wednesday, will ride Emerald City.

Cahill is a big fan of Invincible Express who he believes can go on to bigger things.

"I know it was only a midweek standard Class Six but she had a big weight and a bad barrier. She did a very good job to win," he said.

Cahill and Vandyke are proving a formidable team with Invincible Express's win their 19th for the season.