Northampton: Ramm; Freeman, Odendaal, Dingwall (capt), Hendy; Smith, Mitchell; Iyogun, Langdon, Davison, Mayanavanua, Coles, Kemeny, Pollock, Augustus.
Replacements: Walker, West, Millar Mills, Lockett, Pearson, James, Hutchinson, Furbank.
Castres: Chabouni; Palis, Botitu, Goodhue, Baget; Le Brun, Fernandez; Walcker, Barlot, Collier, Maravat, Nakarawa, Babillot (capt), Delaporte, Papalii.
Replacements: Zarantonello, Guerois-Galisson, Azar, Meka, Macurdy, Cope, Perrone, Dumora.
Referee: Andrea Piardi (Italy)