Mercurial Lad's upset win at Randwick has been greeted by tears and smiles, giving many of those associated with the horse a brief respite from the devastation of the NSW bushfires.

Mercurial Lad is trained by Barbara Joseph and her sons Paul and Matt who operate stables at Canberra and also the Sapphire Coast which is under siege.

The stable is housing displaced horses at the south coast property and their neighbours and friends are doing it tough.

Mercurial Lad was a $51 chance but kicked strongly under vigorous riding from Rachel King to beat Destiny's Hero.

Matt Jones is related by marriage to Robert Salway, 63, and his son, Patrick, 29, who died fighting to save their property at Cobargo last week.

"This means a lot to a lot of people," Paul Jones said.

"My brother Matt's wife, her family paid the ultimate price at Cobargo.

"But things fell into place today. We got Rachel back on and he gutsed it out."

Jones said two of Mercurial Lad's owners, Andrew Mills and Scott Chapman had stayed home at Bateman's Bay on Saturday to try to protect their homes from the fires.

Adding to the emotion of the win, Jones said Heath Parker, Mercurial Lad's regular track rider, was diagnosed with leukaemia three weeks ago.