The No. 8’s stoppage-time try, his third of the match, earned already-qualified Quins their fourth pool win from four games, with three having been dramatic affairs.

He told BT Sport: “We showed great resilience and we just stay in the fight. We know with the quality that we’ve got and that resilience that we can win these games.

“We were just trying to stay as calm as possible really. Just one or two messages and go and focus on that next job, and we did that really well.

“At the start of the season, we targeted that we wanted to get into the knockout stages. The club hasn’t done that for quite a long time. So, to go four from four is great for us and we look forward to the knockout stages.”

Quins defence coach Jerry Flannery admitted to mixed feelings as he watched the dramatic climax.

He told BT sport: “You put your coach’s hat on and it it’s not what you want to see, but from a rugby fan perspective, it’s pretty incredible.

“The belief that’s in the dressing room is something else. They just don’t know when they are beaten.”

Flannery praised Castres for giving the English champions such a difficult match.

“I have to give credit to Castres, because a lot of people probably wrote them off, as they were coming off the back of three losses in the Champions Cup, but they are a really good side,” he commented. “That’s why they are third in the French league and they made it really, really hard for us.”

Quins’ quest for European glory continues when they face Montpellier Hérault Rugby in the last 16 in April.

Harlequins matchwinner Alex Dombrandt hailed his side’s never-say-die attitude as they pipped Castres Olympique 36-33 in Round 4 of the Heineken Champions Cup to end their Pool B campaign in style.