CSU put in their best performance of the season to set up a clash with Griffith for a place in the women’s sevens grand final.
Reddies dominated Waratahs to score their first win over their crosstown rivals this season.
Getting on top early, coach Andy Bedford thought the team’s physicality proved to be the difference as they went to claim a 36-14 win.
“It was a good win and I was very impressed,” Bedford said.
“The big difference was we were way more physical than we have been against them in our first two games.
“Our defence really rattled them and forced them into pushing that pass, forced a lot of errors and turned that ball over.
“To our girls credit every time we got half an opportunity we converted that into tries.”
Two tries from Biola Dawa helped the team take a 15-7 lead into the break.
Waratahs scored right on half-time to get back into the game but it was all Reddies in the second half.
Sophie Thomson scored early before the Dawa completed her hat-trick.
Waratahs got one back before Emma Hickey crossed in the last play of the game to see CSU finish on a high.
Captain Brittney Bedford led the way up front while Hickey was also strong.
There has been little between Griffith and CSU this season Bedford is looking for team to continue their good form when they clash in the major semi-final.
“If we keep that intensity, play like we did and support each other I’ve got no doubts we can win,” he said.
Reddies are the only team to have got the better of the minor premiers so far but they fell 20-17 when the two last met in June
Meanwhile Waratahs will be playing for their season when they tackle premiers Leeton at Conolly Rugby Complex on Saturday.
The Dianas scored on the last play of the day to take a 20-17 win to knock Tumut out of the running.
However they will need to step up against a side coming off just their third loss for the season.