Retired trainer Grahame Begg was not the only one having doubts about unraced filly Mossin' Around.

Jockey Tye Angland also needed some convincing while trainer John Thompson was hardly oozing confidence before the TAB.com.au Maiden Handicap at Canterbury on Wednesday.

Begg, a Group One-winning trainer who closed his Randwick stables a year ago, shares ownership in Mossin' Around after paying $30,000 for her as a yearling.

And with a bonus attached, Mossin' Around's win as a $71 chance more than recouped her purchase price after Begg questioned her future as a racehorse following a recent barrier trial.

She was the second outsider to win in as many races after Raised A Legend also won as a $71 long shot.

"You couldn't have her on the trials," Thompson said.

"I'm a bit casual with my horses with the way I train but Grahame actually asked after the last trial if she was worth going on with."

Thompson said it was only after the barrier trial that he started to get serious with Mossin' Around.

"I pressed the button a bit and she improved out of sight and then you've seen that today," he said.

Angland admitted he had to trust Thompson's judgment.

"You are correct, she's going better than she trialled," the jockey told Thompson as he returned to scale.

Thompson said it was a privilege to prepare a horse for Begg.

"I wear it as a badge of honour that a colleague like Grahame gives you a horse to train," he said.

Mossin' Around came down the outside to beat the Chris Waller-trained favourite Tsaritsa ($4.60) in the last stride, denying visiting Irish apprentice Pat O'Donnell his first metropolitan win in Australia.