The Williams trio of Rhodri, Scott and Jordan did the damage against the Quins and looking ahead to tomorrow's game, head coach Simon Easterby has told his players they must back up a positive result with a solid performance on home soil.
"We've got our feet on the ground but there's no doubt last weekend's performance has boosted confidence and spirits," said Easterby.
"Getting a win in Europe was a mental hurdle we needed after last season but it won't mean anything if we don't perform against Racing.
"This is a big opportunity for us to kick on. If we get our house in order and we're at our best, we know we can match the top sides."
Easterby is boosted by the availability of Rhys Priestland who was an injury doubt earlier this week. The Wales fly half starred in the win over the Quins and will again be hoping to release his dangerous outside backs tomorrow evening.
"When you have backs of the quality and talent of Liam Williams, Scott Williams, Jordan Williams, Rhys Priestland and Jon Davies, then you know you're going to try and play a certain way," said Easterby.
"We respect we are coming up against a very dogged Racing side. They haven't conceded many tries this season and the threats from their scrum and driving line-outs are clear to see.
"Add to that the quality of players they have in their ranks and the depth of squad at their disposal and we acknowledge this is a huge challenge in front of us."
Easterby makes two changes from the side which won last weekend. Hooker Ken Owens is still on the side-lines with an abdominal strain while Rob McCusker is still out with a calf injury so Aaron Shingler, John Barclay and Josh Turnbull continue in the back row.
Nick Reynolds comes onto the wing to replace the injured Kristian Phillips with South African Prop Jacobie Adriaanse coming in for the suspended Samson Lee.
Racing include Wales flanker Dan Lydiate as well as fellow British & Irish Lion Jonny Sexton at fly half.