John Mulvihill has called for a complete performance in next week's return clash against Saracens as injuries took their toll at Allianz Park.
Cardiff Blues, who were already without nine front-line players, battled to an 18-13 half-time lead in London thanks to tries from Blaine Scully and Matthew Morgan.
But further injuries to Lloyd Williams, Jason Harries and Jarrod Evans proved costly as the English champions showed their quality in a devastating second-half display.
Mulvihill was pleased with the first-half performance from his side and has called for more ahead of next week’s return clash, while revealing several absentees will return for the Arms Park showdown.
He said: “It was an excellent first 40 minutes, they came out of the blocks and are a class outfit and scored first. We did really well to claw our way back into the game and 18-13 at half-time, we were in the game.
“We had a few significant injuries towards the end of the half and two of them were main backs in terms of Lloyd Williams and Jarrod Evans. That left us a bit short and with about 20 minutes to go we had no backline replacements – we were running on empty.
“But we need to learn from what we did well in the first-half and what let us down in the second-half and put in a complete 80-minute performance.
“We have a few players coming back for next weekend but it just goes to show the quality of their squad and the depth they have got and probably the depth we lack. We will be looking hard at what our team will be next week but a silver lining is we get a few boys back next week.
“They had a few guys missing as well, which is scary but they have good depth and will be in to qualify and will bring their best team. It will be great to welcome some of our boys back to the Arms Park.”
With the Arms Park heading towards a sell-out it promises to be a red hot occasion in the Welsh capital and Mulvihill is acutely aware of the importance of an 80-minute performance as three consecutive Welsh derbies approach.
He added: “That is fantastic and is reward for how well they went last year. It is important that we arrive ready to go and put in a performance in front of our home crowd next week ahead of the Dragons the week after.
“We have an eye on those big three PRO14 derbies and three wins would set us up nicely but we are still focussed on the Heineken Champions Cup and we will prepare a team to win next week.”
The only remaining tickets for the Arms Park encounter are in the North Terrace and they are selling fast. Click here to buy yours today.