Dublin’s Aoife Clark and Master Crusoe are 12th overnight after the first day of dressage in the eventing competition at Greenwich Park at London 2012.
The duo recorded a penalty score of 48.90, which gives her a marked advantage when she begins the next phase of the event on Monday.
Cork's Michael Ryan was the first of the Irish team into the arena with Ballylynch Adventure, finishing on a score of 60.20, while Mullingar's Joseph Murphy completed the day on 55.60 penalties with Electric Cruise.
Germany's Ingrid Klimke leads the overnight rankings with Butts Abraxas on 39.30.
A total of 74 horse-and-rider combinations make up the 13 nations taking part as teams and individuals in eventing.
Ireland currently lie fifth in the team competition.
Sunday sees Kildare's Camilla Speirs and the petite Portersize Just a Jif enter the dressage arena at 11.52, with Ireland's last team member, the experienced Mark Kyle from Wicklow, performing his test with the grey Coolio at 15.10.
The second phase of the eventing competition is the cross-country, which takes place on Monday, followed by show jumping on Tuesday.