Winona Costin will have surgery after being injured in a trackwork fall.
The leading apprentice suffered a laceration to her leg while riding work at Rosehill on Thursday morning.
Costin's mother Trish told Racing NSW her daughter will be operated on in Sydney's Prince Of Wales Hospital.
Last season's champion apprentice in Sydney, Costin has only recently returned to riding after she was injured in a race fall at Grafton in April.
Costin's book of five rides at Rosehill on Saturday included Ravi, favourite to make it back-to-back wins as the three-year-old takes on her own age over 1200m.