Dave Ward came onto the pitch as a replacement flanker but his efforts earned him man of the match, as Harlequins scored a last-gasp bonus-point try in their 32-20 victory over Cardiff Blues.
Harlequins had kicked off the European Rugby Challenge Cup with a 41-18 triumph against Montpellier last Thursday but they were forced to respond to adversity early on at BT Sport Cardiff Arms Park.
They lost James Chisholm and skipper for the night Jack Clifford in the opening 30 minutes, forcing hooker Ward to take to the field in an unfamiliar position.
His all-action display inspired Conor O’Shea’s men to pile on the points in the second half, with Tim Visser and Ollie Lindsay-Hague scoring two quickfire tries.
Charlie Walker added a third try on the hour to all but seal victory, and after Matthew Rees was sent off for a stamp on Nick Easter, Danny Care’s typically predatory effort in the last minute secured the bonus point.
“The boys were fantastic tonight, and playing alongside Nick Easter and in-front of Danny Care makes it quite easy, I just ran around and looked for the ball," said Ward.
"I was just hanging around with Nick, he draws defenders in and I just tried to sneak in where there was a bit of space.
"What a dream start to the competition for us, we had an unbelievably tough game last week and to come down here to get five points just shows how strong we are as a squad at the moment.
"We want to win this competition, make no bones about it. We're here for the long haul.
"We're looking to play with the sort of tempo we showed at the end there, we're looking to score from anywhere, whether that be our five metre line or theirs.
"You see guys like Ollie Lindsay-Hague and Tim Visser with the ball in hand – if you give them 50 metres of space, you are not going to stop them. We see it every day on the training ground."
Defending Challenge Cup champions Gloucester Rugby also made it two out of two in Europe this year with a comprehensive performance against La Rochelle.
England No.8 Ben Morgan and Julien Audy exchanged tries early on but it was the boot of Scotland international Greig Laidlaw that put the Cherry & Whites in the ascendancy.
He notched 14 points in the first half alone and Gloucester ended the match with a flourish through Steve McColl and Charlie Sharples tries, though the bonus point eluded them in their 33-20 win.
But it left director of rugby David Humphreys no less satisfied with a win in France.
"We're delighted with the win, delighted with the character and it's always important to keep the momentum going in this competition,” he said.
"There were patches of the game where we were quite good, some of the things we did well, some we made mistakes but to come away to France and win is a tough thing to do, especially against La Rochelle.
"We knew how physical the game would be, particularly in the second half as the conditions deteriorated, there was a bit of rain, we were playing into the wind and it was going to be hard to handle.”
Cardiff Blues 20 Harlequins 32
Tries: Penalty, Hobbs
Conversions: Evans 2
Penalties: Patchell 2
Tries: Visser, Lindsay-Hague, Walker, Care
Conversions: Botica 2, Swiel
Penalties: Botica 2
Referee: Alexandre Ruiz
La Rochelle 20 Gloucester Rugby 33
Tries: Audy, Easton
Conversions: Fortassin 2
Penalties: Fortassin 2
Tries: Morgan, McColl, Sharples
Conversions: Laidlaw, Twelvetrees 2
Penalties: Laidlaw 4
Referee: Marius Mitrea
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