Rumours were rife that immediately after this Heineken Cup Pool D confrontation Cardiff would get on to their coach, steaming not just from their post- match shower but also from the ill-feeling that had hung around following the previous meeting between these two clubs as well as a couple more grouses from this latest clash, and take themselves back down the M4 motorway, with not a pause for a pie or a pint in the clubhouse.
In fact they stayed, had a few bevvies, and the odd beef, before heading west but all was not well. One Cardiff player said of Thierry Lacroix's last-minute penalty miss which could have won the game for Harlequins: "There was a certain poetic justice in that." Lacroix had been the subject of Cardiff claims that he had allegedly kicked one of their players in the head in their first encounter two weeks ago. Quins refused to take action after viewing the incident from a different angle, thus incurring Cardiff displeasure. That was the match after which Quins cited the lock Tony Rees for a crude tap dance on Gareth Llewellyn. Rees picked up a 90-day ban as a result.
While Cardiff channelled their aggression into a breathtaking first half performance which eclipsed Harlequins, they had time afterwards to reflect on what they felt were some unnecessary and ugly moments in a stirring second half during which Quins' Laurent Cabannes was shown the yellow card after clashing with Mike Hall.
The Cardiff centre suffered severely bruised ribs and had to leave the fray and there were dark mutterings from the Welsh camp about taking the matter further if the injury were more than bruising. Two years ago Cardiff, acting for Hall, persuaded Llanelli to pay pounds 1,000 for loss of earnings after Tony Copsey broke Hall's jaw and put him out of the game for five weeks.
Cardiff were also unhappy with one or two other incidents in the match involving the Lacroix and Quins lock Bill Davison. Jonathan Humphreys, their captain, said: "We are not a side to go round citing players, that is not our style."
The Cardiff coach Alex Evans added: "We will be inviting Harlequins to look at the video."
Andy Keast, the London club's director of rugby, needs no prompting in that area. "I will study the video before anyone has a chance to send it to me. I will go through it and if I feel there is action to be taken in-house, then I will take it. I do not need telling about something like that."
Thankfully the niggles and grumbles about isolated incidents took nothing away from what turned out to be a great spectacle. Quins could not live with Cardiff in the first half, the Welsh club would have done a recycling plant proud so efficient were the forwards at delivering the ball into the eager hands of their backs.
They set out their stall after 26 seconds when Lee Jarvis was allowed the space and the time to land a drop goal. Robert Howley, Steve Williams and and Leigh Davies scored a try apiece and Jarvis converted the lot.
Victory looked in the bag until a spirited Harlequins opened it after the restart and ran at Cardiff from everywhere with two of their tries springing from moves begun in their 22.
If Lacroix's conversion of Laurent Belligoi's first try had gone over instead of hitting an upright, or if the Frenchman had been on target with a penalty in the last moments of the match Quins would have rivalled Lazarus for coming back from the dead.
As it was Welsh honour, to a degree, was satisfied. Now all Harlequins have to do to clinch a quarter-final spot is beat Munster in Limerick at the weekend.
Harlequins: Tries Belligoi 2, O'Leary; Conversions Lacroix 2; Penalties Lacroix 4. Cardiff: Tries Howley, Williams, L Davies, Booth; Conversions Jarvis 3; Penalty Jarvis; Drop goal Jarvis.
Harlequins: J Williams; D O'Leary, W Carling, J Ngauamo (S Power, h-t), L Belligoi; T Lacroix (capt), H Harries; M Cuttitta, T Billups (K Wood 18-26, 50-52, 63), J Leonard, B Davison, G O Llewellyn, R Jenkins, L Cabannes, G Allison.
Cardiff: R Ross; N Walker, L Davies, M Hall (J Hewlett, 70), S Hill (M Silva, 56); L Jarvis, R Howley; A Lewis (P Booth, 60-66, 73), J Humphreys (capt), D Young (L Mustoe, h-t), J Tait, D Jones, S Williams, G Jones, E Lewis (J Ringer, 66).
Referee: E Murray (Scotland).