Biarritz visit Vicarage Road on Sunday for a Heineken Cup showdown with Pool Five leaders Saracens
The English champions are only two points ahead of the two-time finalists and the winners of this intriguing tussle will put themselves in pole position for a quarter-final place.
Sarries, who returned to top flight European competition for the first time in three years last season, know a victory over the Basques will guarantee them a place in the last eight.
The French side face a tough final two weeks of the tournament with their trip to Watford this weekend followed by the visit of the Ospreys on the final weekend of the Pool stages and know they must win in England to keep their own hopes of a quarter-final place alive.
In team news, Saracens Director of Rugby Mark McCall brings prop Carlos Nieto and flanker Kelly Brown back into the hosts' starting team.
Those changes see Matt Stevens and Jackson Wray move to the replacement's bench.
"A look at the Top 14 table will show Biarritz currently in the bottom three, but that position far from reflects the quality in their squad and indeed, three recent wins in the competition have seen them climb from the foot of the table and I am sure that rise will continue," said McCall.
"We saw their quality and the dangerous players they possess when we made the trip to France in November. Damien Traille, Dimitri Yachvili and Imanol Harinordoquy are just a selection of the names in the Biarritz squad who boast great European and international experience and we know that we will have to be at our best.
"We couldn't have asked for a better week of preparation for this game having spent the week in Cape Town, enjoying the fantastic facilities and weather in the city while also being able to spend some time away from the rugby pitch to recharge the batteries ahead of a massive game against one of Europe's top sides."
Meanwhile, France loose forward Imanol Harinordoquy will start on the Biarritz bench as the returns from injury.
Former England international Iain Balshaw is at full-back and Argentine drop-goal specialist Marcelo Bosch is preferred to Julien Peyrelongue at fly-half.
Charles Gimenez is given the nod ahead of Benoît Baby at outside centre while France's most-capped prop Sylvain Marconnet provides experience on the bench.
Saracens: 15 Alex Goode, 14 David Strettle, 13 Owen Farrell, 12 Brad Barritt, 11 Chris Wyles, 10 Charlie Hodgson, 9 Ben Spencer, 8 Ernst Joubert, 7 Andy Saull, 6 Kelly Brown, 5 Mouritz Botha, 4 Steve Borthwick, 3 Carlos Nieto, 2 John Smit, 1 Rhys Gill.
Replacements: 16 Jamie George, 17 Petrus du Plessis, 18 Matt Stevens, 19 George Kruis, 20 Jackson Wray, 21 Peter Stringer, 22 Adam Powell, 23 James Short.
Biarritz Olympique: 15 Iain Balshaw, 14 Taku Ngwenya, 13 Charles Gimenez, 12 Damien Traille, 11 Ilikena Bolakoro, 10 Marcelo Bosch, 9 Dimitri Yachvili, 8 Florian Faure, 7 Benoit Guyot, 6 Wenceslas Lauret, 5 Pelu Taele, 4 Jérôme Thion, 3 Francisco Gomez Kodela, 2 Romain Terrain, 1 Fabien Barcella.
Replacements: 16 Arnaud Heguy, 17 Sylvain Marconnet, 18 Eusebio Guinazu, 19 Manuel Carizza, 20 Imanol Harinordoquy, 21 Julien Peyrelongue, 22 Benoît Baby, 23 Dane Haylett-Petty.
Date: Sunday, January 15
Venue: Vicarage Road, Watford
Kick-off: 15.00 GMT
Referee: George Clancy