THERE are two types of Biarritz teams – those with Dimitri Yachvili conducting the orchestra, and those without. When the scrum-half plays at full tilt, the Basques are capable of beating just about anyone. Without him in tune, theirs is often a lost cause.
Unfortunately for Connacht, Biarritz will have the France No 9 taking the baton this weekend. And if the veteran playmaker is at his best – and it's seldom he isn't in European competition – he is capable of unleashing terror on Connacht.
The French side were also boosted by the return of their talismanic captain Imanol Harinordoquy in time for last weekend's Top 14 win over Bordeaux. If Yachvili represents the romantic beautiful game of the Basques outfit, then their No 8 is the hard external shell. He is the immoveable object the Connacht forwards will find in their path tomorrow night.
Harinordoquy doesn't do backward steps and, as Connacht's ball-carriers will discover, he doesn't tend to leave a lot behind him when he hits.
He is also a hugely effective offensive weapon in the Biarritz arsenal. He has never seen a roadblock he isn't inclined to charge and if he and Yachvili are in song, Connacht will be in trouble.
Eric Elwood's side are not without hope, however. The schizophrenic nature of Biarritz this season was highlighted in their Heineken Cup Pool 3 opener against Harlequins at the Stoop when they were gutted ruthlessly.
They were excellent in the first half despite coughing up an early try to Danny Care and they responded with such fire and spirit that they were level at 13 points each at the break.
Biarritz looked irresistible at this stage. They flattered to deceive, however, as they failed to score in the second half. Harlequins relentlessly smashed them up front and powered to a bonus-point win, emphasising the growing belief that Biarritz remain a side in decline as they struggle to find replacements for their ageing stars.
Harlequins remain in control of Pool 3 with nine points. Biarritz are on five points and Connacht are still alive with four. Both sides desperately need to win tomorrow night to retain any realistic hope of catching the English Premiership side.
It's an astonishing situation for Biarritz, previously one of the standard bearers in the Top 14, to find themselves in. Their budgets usually dwarfed their European opponents and everybody else in France as well, with the notable exception of Toulouse.
It has, though, been inescapable in recent years that they have been usurped by the likes of Clermont and Toulon. They are still a force to be reckoned with in Europe – as last season's Amlin Cup success bears out – and their quest for a first ever H-Cup (as it is called in France) title is beginning to take on an obsessive visage.
Twice they have reached the final of the competition. In 2005-06 they came up against a manically obsessed Munster who wouldn't countenance what would have been a third final loss. Then in 2009-10 they came up short in the decider against Toulouse.
They have reached the quarter-finals eight times – although it is noteworthy that they have drawn Italian teams in their group eight out of the last nine years – but their inability to go all the way in the competition remains one of the great mysteries of the Heineken Cup, as does their fluctuating form.
Last season, for example, in the third round they suffered the embarrassment of being turned over by Italian side Treviso. That both Yachvili and Harinordoquy were absent that day emphasises just how important this duo remain to the side.
To have any realistic chance of taking their scalp, Connacht will need to find a way of nullifying this pair's considerable influence, although even at that Biarritz have quality sprinkled liberally throughout their squad, including former England full-back Iain Balshaw and France centre Damien Traille.
If they turn up to play, especially infused with the traditional Basque spirit and competitive qualities, it's hard to see Connacht getting any change from the encounter.
Biarritz are well adrift in their domestic Top 14 competition – lying seventh, a massive 19 points off leaders Toulon – and will see Europe as an avenue to redemption, much as they used the Challenge Cup vehicle last season. Had they not won the secondary European competition they would not be playing in this year's marquee tournament.
They will build their foundations for victory around a bruising forward game, with Yachvili pulling the strings to an unrelenting slow tempo behind them.
They will look to crush Connacht's spirit with the patience and devastation of a python. Every mistake made by a Connacht player will result in Biarritz tightening their hold, and every transgression will be ruthlessly punished by Yachvili's boot.
The hope from out west is that the 'other' Biarritz side turn up. That the players will take one look at the tight confines of the Sportsground, take in the (probable) driving wind and rain and the just-above-zero temperatures and turn up their Gallic noses in disgust.
If that happens, Elwood's men have a chance. Connacht have shown that they can on occasion take the big scalps, most notably against Harlequins last January when they denied the Premiership side a place in the quarter-finals by recording an unlikely 9-8 win.
That victory was forged on the old-school values of manic tackling and 'ball-up-the-jumper' rugby that has always been an art form for Irish sides.
That Connacht were seeking to end a 12-match losing sequence was a huge motivation for them that night and whether or not they can replicate that sort of controlled frenzy again is the question facing them tomorrow.
If they, can they have a chance. If not, it's hard to see anything other than a French celebration.