Nico de Boinville will visit a specialist on Friday after damaging his thumb in a fall at Chepstow on Tuesday.
De Boinville was riding Before Midnight for his boss Nicky Henderson when he was unshipped at the second-last flight in an extended two-mile-three-furlong maiden hurdle.
The rider, who counts Altior and Might Bite among the horses he has to look forward to this season, is now facing a spell on the sidelines.
De Boinville told his Unibet blog: “I damaged my thumb when unseating on Before Midnight at Chepstow on Tuesday, and I am off to see a specialist tomorrow.
“That will tell us where we go next, and the timescales involved, but I am not going to be back within days.
“All jockeys look on the bright side in these situations though, and the aim is to be back in the saddle as soon as possible.
“However, you have to rein yourself in and be guided by the professionals, and tomorrow will tell us more.”