Clermont secured a home Heineken Cup quarter-final on Saturday after running nine tries past Viadana in a 59-20 rampage in Italy.
The French side, who registered a convincing 27-6 win against Ospreys last week, knew that only a bonus point win would see them through to the last 16 and were 7-0 ahead within two minutes thanks to a converted Morgan Parra try.
The away side then ran riot through the feeble Italian defence and had picked up the four tries required for a bonus point by half-time, with Napoleoni Nalaga and Aurelien Rougerie (twice) touching down.
Vern Cotter's team then moved into a commanding 52-6 lead thanks to tries from Julien Malzieu, Elvis Vermeulen, Nalaga and a penalty try, while Brock James continued his fine form with the boot by kicking six straight conversions.
Julio Garcia's converted try gave the home side some hope but Clermont soon hit back to open up a 59-18 lead thanks to a try from full-back Anthony Floch.
Viadana grabbed another a try through replacement Gareth Krause but it was not enough to stop Cotter's side moving to the top of Pool Three at the expense of Ospreys.
Tries: Garcia, Krause
Tries: Parra, Rougerie 2, Nalaga 2, Vermeulen, Malzieu, penalty try, Bonnaire
Cons: James 5, Floch 2
Yellow card: Pierre (Clermont)
Viadana:15 Garry Law, 14 Kaine Robertson, 13 Sam Cox, 12 Lloyd Johansson, 11 Matteo Pratichetti, 10 Pierre Hola, 9 Pablo Canavosio, 8 Jaco Erasmus,7 Andrea Benatti, 6 Aaron Persico, 5 Sean Hohneck, 4 Carlo del Fava, 3 Julio Garcia, 2 Luigi Ferraro, 1 Plinio Sciamanna.
Replacements:16 Roberto Santamaria, 17 Luigi Milani, 18 Mattia Cagna, 19 Quintin Geldenhuys, 20 Gareth Krause, 21 Andrea Brancoli, 22 Josh Sole, 23 Samuele Pace
Clermont:15 Anthony Floch, 14 Napoliani Nalaga, 13 Aurelien Rougerie, 12 Gonzalo Canale, 11 Julien Malzieu, 10 Brock James, 9 Morgan Parra, 8 Julien Bonnaire, 7 Alexandre Lapandry, 6 Jamie Cudmore, 5 Thibault Privat, 4 Julien Pierre, 3 Davit Zirakashvili, 2 Mario Ledesma, 1 Thomas Domingo.
Replacements: 16 Willie Wepener, 17 Lionel Faure, 18 Martin Scelzo, 19 Elvis Vermeulen, 20 Alexandre Audebert, 21 Kevin Senio, 22 Tasesa Lavea, 23 Brent Russell.
Venue: Stadio Luigi Zaffanella