Despite winning the reverse fixture at the Twickenham Stoop last time out, the European heavyweights have opted to switch things around for the immediate return on home soil.
Scrum-half Jean-Marc Doussain comes into the starting line-up ahead of Luke Burgess, while Yann David replaces Florian Fritz at outside centre.
In the pack, Shaun Sowerby comes off the bench to swap places with Louis Picamoles at number eight, suggesting that the hosts will look to move the ball around more than last week on the fast surface of the Stadium de Toulouse.
Yannick Nyanga drops to the replacements so Jean Bouilhou gets a start at flanker and France lock Romain Millo-Chluski returns to the second row.
Up front, Yohan Montes is rotated with Jean-Baptiste Poux. Former Harlequin Gary Botha also loses his starting place, William Servat getting the nod instead.
Harlequins have also made a handful of changes as they look to bounce back from their first defeat of the season.
The Aviva Premiership leaders saw their perfect record end at 14 games with a 21-10 reverse in front of their own fans, meaning Toulouse took over at the top of Pool Six.
To make matters worse for director of rugby Conor O'Shea, Joe Marler and Maurie Fa'asavalu both picked up injuries in the defeat.
Mark Lambert takes Marler's place in the front row while Will Skinner joins captain Chris Robshaw and Nick Easter in the back row.
Joe Gray comes back into the starting line-up with Chris Brooker dropping to the bench as part of the continued hooker rotation policy from the coaching staff.
In the backs, Tom Casson returns from an ankle injury at inside centre alongside Matt Hopper, whilst Ugo Monye is ready to start again after returning from injury over the past two weeks.
Toulouse: 15 Maxime Medard, 14 Vincent Clerc, 13 Yann David, 12 Yannick Jauzion, 11 Timoci Matanavou, 10 Luke McAlister, 9 Jean-Marc Doussain, 8 Shaun Sowerby, 7 Thierry Dusautoir, 6 Jean Bouilhou, 5 Romain Millo-Chluski, 4 Yoann Maestri, 3 Census Johnston, 2 William Servat, 1 Yohan Montes.
Replacements: 16 Gary Botha, 17 Jean-Baptiste Poux, 18 Daan Human, 19 Gregory Lamboley, 20 Yannick Nyanga, 21 Louis Picamoles, 22 Luke Burgees, 23 Florian Fritz.
Harlequins:15 Mike Brown, 14 Seb Stegmann, 13 Matt Hopper, 12 Tom Casson, 11 Ugo Monye, 10 Nick Evans, 9 Danny Care, 8 Nick Easter, 7 Will Skinner, 6 Chris Robshaw (c), 5 George Robson, 4 Tomas Vallejos, 3 James Johnston, 2 Joe Gray, 1 Mark Lambert.
Replacements: 16 Chris Brooker, 17 Nic Mayhew, 18 Kyle Sinckler, 19 Charlie Matthews, 20 Luke Wallace, 21 Richard Bolt, 22 Ben Urdapilleta, 23 Tom Williams.
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