Zac Purton made the most of rival Joao Moreira's suspension and maintained a deadly seasonal strike rate with trainer John Size as promising stayer Ensuring continued his late season progression.

Purton had only ridden one other horse for Size this season, and won when it mattered too, with the pair combining to win the Hong Kong Derby with Luger in March.

This time, with Size's go-to man Moreira cooling his heels due to a whip suspension picked up at Royal Ascot, Purton was again called upon and produced on Ensuring.

"No wonder Joao rides so many winners," joked Purton as he came back to scale on a still-improving four-year-old import that has finished the season strongly after a slow start. Ensuring has now won four from 11 for Size, who said the gelding had overcome the usual on-track challenges faced by many northern hemisphere-bred imports.

"It took this horse some time to get used to the speed of the tracks and the speed of the races," the trainer said. "But he has been very brave, he has applied himself and persevered to make a horse of himself. He still hasn't had a lot of racing and I don't think there is any reason why he wouldn't improve as a five-year-old."

Purton added that although Ensuring had a few things in his favour, including a decent draw from the tricky 2,000m starting point and a solid tempo, there was still a lot to like about the way the winner let down.

"He got into a nice rhythm but he still did have to show a nice turn of foot to chase down Dynamism, but he pinned his ears back and went after it like he really wanted to win," he said. "Obviously there are more things in store for him."

Ensuring's win gave Purton a double after Bright Concept finally broke through at his 18th start, the four-year-old's second outing since a recent stable transfer to Chris So Wai-yin.

"He is a lovely looking horse with a beautiful big action, but he has just been very weak and it has taken him a long time to mature," said Purton, who had ridden the horse six times previously. "He is still pretty weak and he should have put that race away today a bit more comfortably than he did, but I think he can continue to improve.

"He has always worked like he is much better than where his rating ended up and down in Class Five, hopefully he takes some confidence and he can show us what he has really got."