|Harlequins: (6) 25|
|Tries: Care Cons: Care Pens: Evans 6|
|Castres: (3) 9|
|Pens: Kockott 3|
Harlequins kicked off the new European Rugby Champions Cup with a solid win over French side Castres in Pool Two.
Quins were on top in the first half but the match was level at the break, after a penalty apiece from Rory Kockott for Castres and Nick Evans for the hosts.
But Evans took Quins out to a 12-6 lead and the Londoners claimed the decisive score when England scrum-half Danny Care raced on to Evans' kick ahead.
Evans converted and added two late penalties as Quins stretched clear.
After the bitter political battles fought off the pitch that eventually led to the creation of the Champions Cup in place of the Heineken Cup, similar ruthlessness was called for on the field of play, but it was a night when defence dominated attack for the vast majority of the game.
A penalty apiece for the visitors' South Africa-born, now French-qualified scrum-half Kockott and home fly-half Evans saw the scores level at 3-3 a quarter of the way through.
Harlequins enjoyed most of the territory in the first half and had 68% of the possession, and they created a couple of chances, most notably when the lively Care took a quick tap penalty but saw his kick towards England winger Marland Yarde batted over the goalline by Remy Grosso.
But handling errors from the hosts and resolute Castres defence - they made 81 tackles in the first half alone, showing impressive commitment for a side third from bottom of the French top flight - meant there was no further scoring before half-time.
Evans edged the hosts into the lead four minutes into the second half and tit for tat penalties at the scrum - an area where Quins were actually increasingly dominant - saw the game enter the last quarter with the hosts 12-6 to the good.
Despite their endeavour Quins were struggling to break down the Castres defence and it took a moment of magic from former All Black 10 Evans to create the decisive score, chipping and re-gathering before kicking ahead again for Care to outpace the defence.
Evans converted and added a couple more penalties as Quins claimed the only 100% record in the history of the European Rugby Champions Cup - until Saturday, anyway.
Harlequins boss Conor O'Shea:
"We were really ambitious with the way we played in that first half.
"That was not a weak Castres front five, but our scrum and line-out were excellent.
"We have a long way to go, we know that, but this was a real step forward."
Try scorer Danny Care:
"We needed a game like that - it was a real tight affair - and I thought the forwards were outstanding, the set-piece exceptional.
"It was a good team effort but we still want to get better and hopefully we will, but I think it's a step in the right direction.
"We've had an up and down start to the season but you don't win anything in October. Four points today was crucial for us and it sets us up well for next week and our massive game against our good rivals Wasps."
Harlequins: Brown; Yarde, Hopper, Lowe, Tikoirotuma; Evans, Care; Marler, Ward, Collier, Matthews, Robson, Wallace, Robshaw, Easter.
Replacements: Turner-Hall for Lowe (56), Dickson for Care (77), Lambert for Marler (67), Buchanan for Ward (69), Sinckler for Collier (69), Twomey for Robson (73).
Not Used: Trayfoot, Lindsay-Hague.
Castres: Palis; Evans, Tuatara-Morrison, Combezou, Grosso; Tales, Kockott; Taumoepeau, Mach, Montes, Gray, Faasalele, Diarra, Whetton, Bornman.
Replacements: Cabannes for Tuatara-Morrison (75), Lazar for Taumoepeau (48), Rallier for Mach (57), Fa'anunu for Montes (48), Babillot for Diarra (57).
Not Used: Samson, Dumora, Garcia.
Ref: Nigel Owens (Wales).