Part-time teacher Danielle Seib looks to have a genuine Country Championships contender on her hands in Assault'N'Bathory who has surprised the trainer with a first-up win at Randwick.

Seib, who combines high school teaching with training a small team of horses at Goulburn, expected the six-year-old to improve from the run when he resumed in Saturday's TAB Highway Handicap (1200m).

But Winona Costin took Assault'N'Bathory to the lead and he extended his advantage on straightening, holding on to score by 1-1/4 lengths over the fast-finishing Lady Demi with Tale Of The Kraut another half-neck away.

"I thought he was capable of a good run but I didn't quite expect that," Seib said.

"Condition-wise, he does have a lot of improvement but he's just a different horse with the blinkers on.

"A lot of questions were raised over him just being a wet track horse and I always thought he could handle the firmer tracks and it's good to see him do that today."

Seib confirmed she had her sights on the Country Championships Final (1400m) at Randwick on April 4 with the horse likely to have one more start before tackling the qualifying heat at Nowra in February.

"Yes, that's where we're heading," Seib said

"I think he's really taken another step this prep."

Seib, who is looking to expand her team and build on-course stables at Goulburn, also praised Costin's ride.

She said the jockey had worked hard with the horse behind the scenes to help Assault'N'Bathory overcome his early issues in the starting stalls.