The Murdoch-Franklin partnership stood tall in the modest tally of 145 for six, setting the Knights a run chase of just over seven an over. But, for the second time in three days, a relatively low chase was too much for the Knights, Daryl Mitchell leading the reply with just 31.
With opener Anton Devcich and Brad Wilson already back in the pavilion, two big wickets in the seventh over - Watling lbw to Brent Arnel, followed immediately by hard-hitting captain Daniel Flynn run out after a mid-pitch muck-up with Scott Styris - were the last things the home side needed.
Left needing 50 runs from the last four overs, the pressure told as wickets kept falling, the Firebirds successfully restricting their hosts to 124 for nine.
Pace bowling mentor Arnel was delighted with the team's unified effort in the field against his old side: "It was a huge win for us, one very much needed. Our bowlers knew they all needed to do the hard yards, knowing that it was likely going to be a low-scoring game."
The Firebirds face the Otago Volts on Wednesday while the Knights head to Auckland to take on the Aces the same day.