Trainer Luke Oliver admits he'll be disappointed if Black Diamond Girl doesn't make it two wins from as many starts when she makes her city debut at Sandown.

Black Diamond Girl won her maiden by 4-1/2 lengths at Kilmore in December, beating Portion Control who has since won twice including at Sandown.

The three-year-old filly lines up in Wednesday's The Cove Hotel Handicap (1000m) after impressing Oliver in a jump-out win at Caulfield last week.

"She's very fast," Oliver said.

"It's a step up from a maiden but she only knows one speed which is flat out."

He said he was nervous and excited to see what the filly can produce in her second race appearance.

"I'd be disappointed if she got beaten," Oliver said.

Oliver gave Black Diamond Girl a short break after her all-the-way win on debut.

"She had a couple of weeks off and a couple of weeks on the water walker and we've kept her nice and fresh," he said.

The Caulfield trainer said hoped the filly would learn to harness her speed although there wasn't much point fighting her at the moment because was capable of winning doing what she's doing.

"She's very quick but she's also a real bulldog with everything," Oliver said.

"So she won't go fast and stop. She'll go fast and keep going.

"(But) she'll need to pace herself to go up in class."

Wednesday's field includes the John Sadler-trained Star Planet who is entered to race for the first time since August.

Star Planet hasn't won in eight starts but was placed in the Vain Stakes during his last campaign.