The English aristocrats' impressive bonus point 47-8 victory over Connacht in their last Pool game at the Stoop proved they have the pace and the power to be genuine contenders in this season's tournament.
England and Harlequins captain Chris Robshaw will want his side to keep their impressive unbeaten record in the Pool stages as they prepare for the sharp end of the competition.
Qualification is a long shot for the French side, who were Heineken Cup finalists in 2006 and 2010, and they simply have to beat 'Quins to come into the reckoning as qualifiers for the Amlin Challenge Cup quarter-finals.
They will also be looking for revenge for their 40-13 defeat to Harlequins in the Pool opener at the Stoop back in October.
The Basques managed a 32-6 win over Zebre in Italy in their last game but will want to take the scalp of the form side in Europe when they host the Londoners on Friday evening.
- Biarritz have won their Round 6 match for the past 10 seasons.
- The Frenchmen have been defeated only once at Stade Aguilera in the Heineken Cup since 2001 - 6-10 to Cardiff Blues on 13 December 2008.
- Harlequins' only win in their last five Heineken Cup round six encounters was 29-24 at home to Scarlets in 2008/09.
- Quins have made the perfect start in the Heineken Cup this season with five wins out of five - equalling their best start to any ERC season, when they won their first five games in the 2003/04 Challenge Cup (in a knockout format).
- Harlequins average of 45.4 points per match is the highest of all clubs in the Heineken Cup this season.