The job is not yet done: Saracens, the English champions, must take something from their final Pool Five game against Treviso in north-east Italy next weekend to be sure of qualifying for the knock-out stage of the world's best club competition for only the second time in six attempts.
But by squeezing out this narrow victory over Biarritz – or rather, this narrow victory over the extraordinary Dimitri Yachvili, who is to scrum-half play what the Heineken Cup is to rugby tournaments – they put themselves in touching distance of the initial prize and gave the national selectors some serious food for thought as well as a little reassurance ahead of next month's Six Nations business.
Brad Barritt was the man who provided the reassurance. The uncapped centre is a firm favourite to make his England debut in Scotland on 4 February and if he defends at a packed-to-the-rafters Murrayfield as well as he did in this grotty corner of Watford yesterday – Saracens may have their heart in the right place, but their home is very definitely in the wrong one – there will be a rare old scrap for the Calcutta Cup. Indeed, the Premiership side came out ahead here largely because Barritt served up his signature dish in midfield at the last knockings, strangling what might have been a match-winning Biarritz move at birth and forcing Manual Carizza into conceding a penalty that Owen Farrell serenely converted from 45 metres.
That left the Basques in a need of a try, which was unlikely given the exasperating narrowness of their attacking vision, rather than a drop goal, and the Saracens players were quick to do the maths and fell on their midfielder with due enthusiasm.
Nor was it the first time the man from Durban had put himself amongst the visitors to considerable effect: there were at least half a dozen occasions when Marcelo Bosch and Damian Traille were drawn up a dark and inescapable alley by Barritt's sharp line speed and intense physicality.
Where Stuart Lancaster and his fellow England caretaker coaches might have some thinking to do is in the full-back position, for Alex Goode, quite the most intelligent No 15 in the domestic game if far from the quickest, is making out a compelling argument for inclusion sooner rather than later. He was the best player on the field yesterday, which was no mean feat given the scrummaging impact made by the in-form prop Carlos Nieto and Yachvili's craftsmanlike ability to construct silk purses from the sows' ears presented to him by his struggling pack.
"I think he is playing as well now as at any time in the last two and a half years," the Saracens director of rugby Mark McCall said of Goode, who is behind the quicker but less artistically blessed Ben Foden and Mike Brown in the red-rose pecking order but will train with the senior party ahead of the trip to Edinburgh as cover for the injured Toby Flood.
"His international prospects really depend on the style of rugby England want to play. Ireland have worked out ways of playing both Rob Kearney and Luke Fitzgerald by putting one of them on the wing. I don't know if that's a possibility with England, but as far as I'm concerned Alex has a great pair of hands and a great pair of eyes – things you need in a full-back."
Goode displayed put the best of himself here: his happy knack of emerging from apparent dead ends while running out of defence into heavily congested areas was much in evidence, as was the intelligence of his tactical kicking game. While his opposite number, the former England full-back Iain Balshaw, delivered the most eye-catching touchfinders during a second half that grew more fearful and fretful as it unfolded, Goode won their contest in cumulative terms.
Biarritz crossed the water knowing that their future in this season's tournament depended on producing a performance significantly better than anything they managed in French Top 14 rugby between late August and late December – a period in which Yachvili, their most influential individual by many a country kilometre, was largely off-limits thanks to World Cup commitments and resulting injury hassles.
The fact that he was back in the ranks for this match at least opened up the possibility of an upturn, and so it proved. The Basques were not exactly electrifying – even at the best of times, they aim low and hit the bullseye – but Yachvili's unique ability to make an impact on a game always makes them dangerous.
He landed a couple of early penalties, the first much tougher than the second, to give his side a 6-3 lead and it was not until the ball ricocheted from him in midfield at the end of the first quarter that Saracens, who had been unable to capitalise on their clear-cut advantage at the set-piece, made some proper progress. The livewire wing David Strettle was the first to the loose ball, Ernst Joubert and Chris Wyles maintained the momentum down the left and Ben Spencer, fast making strides as a half-back of quality, beat three men in running a line close to the ruck before stretching over for the try.
A couple of Farrell penalties either side of the half-hour opened things up to 14-6, and for a moment it seemed the home side might disappear into the sunset, especially as the Basques' lowly Top 14 placing did little to suggest they might respond positively to adversity. But a couple of early second-half chances went begging and when Yachvili charged down Peter Stringer's defensive clearance and beat Charlie Hodgson over 15 metres to claim the touchdown, Biarritz were back to within a point.
Cue Saracens paranoia and neurosis on a grand scale – conditions finally eased by Barritt's energy and Farrell's cool-headedness. The two of them are likely to fill England's centre positions when the Six Nations gets underway. If only Goode were alongside them, somewhere.
Saracens: Try Spencer. Penalties Farrell 5.
Biarritz: Try Yachvili. Conversion Yachvili. Penalties Yachvili 3.
Saracens A Goode; D Strettle, O Farrell, B Barritt, C Wyles; C Hodgson, B Spencer (P Stringer, 54); R Gill, J Smit, C Nieto, S Borthwick (capt), M Botha (G Kruis, 54), K Brown, A Saull, E Joubert (J Wray, 66).
Biarritz I Balshaw; T Ngwenya, C Gimenez, D Traille (capt), I Bolakoro (B Baby, 67); M Bosch (J Peyrelongue, 54), D Yachvili; F Barcella (S Marconnet, 47), R Terrain (A Heguy, 54), F Gomez Kodela, J Thion, P Taele (M Carizza, 54), W Lauret, B Guyot, F Faure.
Referee G Clancy (Ireland).