The English champions are only two points ahead of the two-time finalists and know a victory over their closest rivals will guarantee them a place in the knock-out stages.
The French outfit face a tough final couple of fixtures with their trip to Watford this weekend followed by the visit of the Ospreys and the Basques must win in England to keep their own hopes of a quarter-final place alive.
Saracens director of rugby Mark McCall restores both prop Carlos Nieto and flanker Kelly Brown to his starting XV for the clash.
Those changes see Matt Stevens and Jackson Wray drop down to the replacement's bench.
McCall - who took his side to Cape Town this week to prepare - insists his team will not be fooled by Biarritz's lowly position in the Top 14 standings.
"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," stated McCall.
As for the visitors, France loose forward Imanol Harinordoquy will start on the Biarritz bench following his return 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 Benoit Baby at outside centre while France's most-capped prop, Sylvain Marconnet, provides experience from 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 Benoit Baby, 23 Dane Haylett-Petty.
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