Moreira led by one at the start of play, but that had extended to four before Purton and Magic Giant struck in the final race on the card.
There was plenty to like about the victory, too, as the Ricky Yiu-trained gelding took another step up the ladder in the Dorset Handicap.
The imposing four-year-old needed help to find his balance at the top of the straight, but once he did he went through the gears and was a cosy two and a quarter lengths to the good at the line.
“He looked impressive in the end, but he was hard work in the run,” Purton said, who is now on the 101-winner mark for the campaign.
“They were too quick for him early, with the big weight he found it too hard to gather momentum at the start – the pace was on pretty much the whole way and the leader kicked for home early.
“Having worked early, off the bit mid-race and chasing early, it was a good tough effort to pick up and still get the job done. The best part of his race was the last 100 (metres), it was really the only time he got going.”
Yiu admits he is “tempted” to try a mile with the Power gelding, but seems set to stick at seven furlongs for now.
“He’ll be up in Class 2 and it’s tempting to go to the mile, but the move up in class and the step up in distance is a lot of work to do at once. Maybe we’ll stay at 1400 metres for one more race,” he said.
Yiu is bidding for a first trainers’ title and the win completed a treble to take his tally for the season to a personal-best 51 winners, further boosting his claims as he leads Francis Lui by four.
He said: “People messaged me to let me know I’d broken my personal record. It’s a great achievement, but if I win the premiership, then I’ll be more than happy.
“Winning these races today has given me a big kick, it’s put a bigger margin on Francis in second. I definitely believe I have a good enough string to go on and win the title.”
‘Magic Man’ Moreira struck with Defining Moment, Foodie Princess and Fantasy
“If I can keep on winning races like today I’ll be extremely happy,” he said.
Racing continues in Hong Kong with the meeting at Happy Valley on Wednesday.
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