A race later the track was, for unrelated reasons, deemed unsafe.
So while it has hardly been a stellar week for track management in this country, Castles is thrilled with how Ellerslie is holding up to a month in which it will host seven meetings.
"Our track was fantastic here on Saturday and was upgraded three times during the day," says Castles.
"For this meeting, we will move the rail out 12m and then back to the 8m mark for Sunday's meeting.
"That will protect the inside ground for the premier week from Boxing Day to New Year's Day."
While Castles knows full well the tricky combination of summer's drying heat coupled with raceday rain, he pointed to Ellerslie track manager Jason Fulford's efforts to keep the Auckland track abandonment-free start months in advance of the summer silly season.
"While the irrigation in the days leading up to the races is important, it is what Jason and his team did months ago that really matter, he explains.
"They turn the track over and aerate it and now, closer to racedays, they pay particular attention to the surface just in front of the starting gates at each point so the horses can stride out early and get confident.
"You can never help bad luck and we feel for those clubs who have had to go through losing a raceday recently but we do our best to mitigate those circumstances."
That becomes especially important when you have a meeting like tonight's, which while only seven races, will have enormous corporate support as Auckland race fans get into their usual December party mode.
The feature of the twilight meeting - on the track anyway - will be the $15,000 Twilight Cup in which Red Dakota shapes as one of the hardest to beat.
The 5-year-old is unbeaten in two starts at Ellerslie and looked unlucky at Pukekohe last start when denied galloping room late.
He is trained by Peter and Dawn Williams, whose strike rate of winners and placegetters has been outstanding since they moved north.
Meanwhile, glamour mare Shez Sinsational looks set to start at Te Rapa on Saturday after being entered for the $85,000 fillies' and mares' group two event.
Mares also headline the $100,000 Waikato Times Gold Cup, with Jeu de Cartes and Dolmabache heading the rating for the next big Cup of the summer.