Northampton reached the Champions Cup quarter-finals after a battling 49-41 win over Castres.
Castres raced into a 12-0 lead inside 10 minutes through tries from Christian Ambadiang and Theo Chabouni, before Saints were awarded a penalty try and Ambadiang was shown a yellow card for a high tackle. Castres were later reduced to 13 players when lock Guillaume Ducat was sin-binned for catching Henry Pollock in the ruck, but they extended their lead with a penalty. Danilo Fischetti then went over and Saints trailed 15-14 at the interval.
The hosts went ahead for the first time five minutes into the second half when Archie McParland’s pass sent Josh Kemeny in, and Tommy Freeman’s score pushed the lead out to 13. Castres fought back with tries from Tyler Ardron and Vuate Karawalevu to cut the deficit to one, but George Furbank and McParland put Northampton back in control.
Vilimoni Botitu reduced the arrears to eight, but Castres lost Veresa Ramototabua to the sin bin and Northampton capitalised when Fraser Dingwall crashed over. Ambadiang finished with a final-minute burst from halfway, but Saints held on to book a last-eight tie with either Bath or Saracens.