The victory edges Sale closer to Pool 5 leaders Brive and Diamond believes if they can complete the double over Agen next weekend they will put themselves in a strong position in the pool with Brive still to visit Edgeley Park in the new year.
"We produced a brilliant first-half display," said Diamond.
"They way we won at Bath gave us the correct mindset to come here and win.
"We got it wrong against Exeter a fortnight ago but we have learnt from that and the big thing is this win means we are right back in the competition.
"We conceded two tries but we defended very well.
"If we can win next week at home to Agen, it bodes well for the Amlin Cup and then we can kick on from there.
"There's a great mentality about the place and hopefully that can see us through to Boxing Day when we play Newcastle in the league."