It has been four years since Ryan Moore has ridden at 53.5-kilograms so his decision to take the ride on Warm Heart at Sha Tin on Sunday cannot be taken lightly.

The Aidan O'Brien-trained three-year-old filly lines up in the Group 1 Longines Hong Kong Vase (2400m) following a  narrow second placing in the Breeders' Cup Filly & Mare Turf (2011m) at Santa Anita last month, and it is no surprise to see Moore sticking with the together with the significance around his riding weight. 

Since 2010, Moore has only ridden in this weight range 24 times or an average 1.8 rides a year. 

Moore generally rides over 600 races a season, which adds further depth to his decision to get down in the weights for Sunday's feature. 

The last time we saw Moore at this weight was in the 2019 Group 1 Beverley D Stakes (1911m) at Arlington when steering home the Aidan O'Brien-trained Santa Barbara to victory.

The other surprise in Hong Kong this week was seeing O'Brien in the lead-up with the prominent trainer usually arriving on Sunday. 

Seen at trackwork throughout the week, O'Brien said they had changed their regular routine and was happy with their build-up, though the answers would come on Sunday. 

"This year we have brought them a little bit earlier and give them a little bit more time to build into it," O'Brien said. 

"I don't think is really any set rule with what works and what doesn't work. It's also dependent on the horse themselves. 

"As a trainer what has worked the time before you are always inclined to go with but when you do that, it might suit some horses, but it doesn't suit others. 

"We felt it was the best approach this time, but we'll find out on Sunday." 

O'Brien also felt this was the best team that his stable had ever brought to Hong Kong. 

"I think there is no doubt that it is," O'Brien said. 

"It's very difficult to win races here and you don't come with second-raters. 

"I'm hopeful, I'm never confident, I'm always hopeful, we've all been around racing long enough now that we know that the strangest things can happen. 

"So hopefully they run well and if one was to win, we'd be over the moon."