The pair started the day tied on 117 winners apiece and ended the evening on 119, with Moreira commenting: "It's such a journey, but it's a good one!"
Purton was first off the mark when Dionysus Collin landed the Tan Shan River Handicap, but Moreira replied immediately with an all-the-way win on Lightning Steed in the Tai Shing Stream Handicap.
Moreira said: "I rode him the time before, but Caspar (Fownes, trainer) said this time it would be a bit different.
"The circumstances today just allowed me to ride the horse how he likes to be ridden and he quickened down the straight in a way that he was never going to get beaten."
Purton then edged back in front with victory aboard Danny Shum's Golden Dash in the Lam Tsuen River Handicap.
"We had a good draw so obviously that helped, but Danny's done a good job to bring him back from injury, he's given him plenty of time and a couple of runs to get him ready for this," Purton said.
Shining Ace then ensured Moreira kept the scores level by landing the closing Ho Chung River Handicap.
"He just loves the wet - when he won with me before it was raining and the ground was soft," Moreira said.
"I was surprised that he was able to bounce out so quickly and challenge those fast horses up there, but as well as he was going, he was never going to stop.
"It's a great training achievement. All the praise should go to John (Size) - he's improved this horse so much.
"Hopefully the winners will keep on coming."