The hosts do have 23 stone-plus Ben Tameifuna on the bench to supplement their set-piece in the second half.
Bath are contesting their first top-tier European semi-final in 20 years since they lost a tryless and bad-tempered encounter with Biarritz 18-9 in 2006.
Toulon and Leinster will face off in the other semi-final on Saturday, with the winners progressing to the final on 23 May at Bilbao’s 53,000-capacity San Mames stadium.
Bordeaux-Begles: Rayasi; Uberti, Penaud, Moefana, Bielle-Biarrey; Jalibert, Lucu (c); Perchaud, Lamothe, Sadie, Palu, Coleman, Bochaton, Woki, Gazzotti
Replacements: Barlot, Boniface, Tameifuna, Cazeaux, Vergnes-Taillefer, Matiu, Retiere, Hugo Reus
Bath: Carreras; Arundell, Hennessey, Lawrence, Muir; Russell, Spencer (c); Obano, Dunn, Du Toit, Roux, Ewels, Bayliss, Pepper, Barbeary
Replacements: Tuipulotu, Van Wyk, Sela, Hill, Underhill, Carr-Smith, De Glanville, Reid