Rebecca Waymouth-trained Acosta won the $5000 Balnarring Cup in front of more than 5700 patrons in perfect conditions.

But to give the victory more appeal, Waymouth's mother Debbie rode the seven-year-old gelding to record her third win in the Balnarring feature.

Her first victory as a jockey in the Balnarring Cup is believed to have come in the late 1980s. "We had only had the horse for 26 days and he had run at Healesville in the Healesville Cup but was probably a bit underdone," Rebecca Waymouth said.

The elder Waymouth played a large role in the victory after Acosta was roughed up early and given some ground to make up.

But the veteran jockey steered Acosta ($6.50) expertly through the field to narrowly defeat Pat Carey's Kissy Lips ($4) with Quinton Scott's Tuscany Lad ($16) over a length away in third.

"He got a bit of interference early and then shovelled back through the field," Rebecca Waymouth said. "He hadn't won in just over three years. It was a very good ride and she rode him like the best horse in the race."

Balnarring Picnic Racing Club secretary Neil Heathcote said the large crowd was "probably a record" and was well behaved.

Entertainer Wendy Stapleton gave the Australia Day address and Paul Norton gave a rendition of his song Southern Sky, which was made internationally famous when performed at the Sydney Olympics.

Balnarring Picnic racing Club holds its next meeting on Labour Day in March before closing its season on Easter Saturday.