A change in training and riding tactics have proven the catalyst for Victorian filly Politeness to score a barnstorming Group Three win at Randwick.

Trainer Robert Smerdon said the three-year-old had long shown talent but failed to live up to expectations, prompting him to tinker with his approach.

"The less I do, the better she goes," Smerdon said.

"I probably made a mistake training her too strong and we were riding her too close. We changed all that round and that's the real horse.

"She's a Group winner now and entitled to be and I think she can go on with it."

Politeness drew the outside stall in the 18-horse PJ Bell Stakes field and settled near the back before unleashing a withering run down the outside.

Backed from $11 into $9, Politeness scored by 1-1/4 lengths over Cosmic Endeavour ($15) with Miniature ($15) another neck away.

Smerdon admitted to some concerns when Craig Williams had Politeness at the tail of the big field, but he was so taken by her finishing burst he will now consider a start in the Group One Sportingbet Classic in Adelaide on April 26.

The Group Three JHB Carr Stakes at Randwick on the same day is also an option.

"She'll go home Sunday. She could come back to Sydney for the James HB Carr Stakes in two weeks or go to Adelaide," Smerdon said.

Williams said Politeness was a class above her rivals on the wet track and won with something in reserve.

"She was dominant," Williams said.

"She got the visitor's draw, but she really played with them today and she's a quality filly."