Lightning struck twice for the Waratahs this season as the Force once again made them unravel with an 18-11 victory in Perth.
The Force had only won once all season before this Round 13 contest; their shock victory over the Waratahs in Sydney right back on the opening weekend.
Since then it's been a collection of disappointments and narrow misses but when the Force are able to win the physical battles and turn games into a war of attrition, their chances automatically improve.
That was exactly happened in Perth, as Matt Hodgson's pack won the narrow battles and the home side looked for territory with the boot rather than prefering to keep the ball in hand like their opponents.
The Waratahs were outmuscled on the opening day but had won five of their last six matches before heading west including last week's narrow derby success in Canberra.
Luke Burton came off the bench early on for Solomoni Rasolea but he couldn't open the scoring with a penalty.
Enjoying most of the early possession the Force hunted for an opening try, but it came from a turnover when Jacques Potgieter lost possession in his 22.
Scrum-half Ryan Louwrens was sharp enough to sweep up the loose ball and then sprint for the line with a good turn of pace, with Burton's conversion putting the Force up 7-0 on the 20-minute mark.
Two quick penalties in three minutes from Bernard Foley close the gap to just a single point before a sustained attack from the Force over multiple phases allowed Burton to reply with his first penalty.
Getting frustrated by the Force it wasn't a surprise to see tempers boil over, with the Wallaby prop Sekope Kepu sin-binned for illegal use of the boot at the ruck when the Waratahs were on the charge.
Each side had a chance to add more points before half-time, with Burton successful for the Force but Kurtley Beale's long-range strike from the halfway line fell short, as the Force held on to a 13-6 advantage.
Eager for a quick start the Waratahs welcomed Kepu back to the fold and then scored an excellent try through their gamebreaking winger Taqele Naiyaravoro.
The 123kg weapon thundered his way through tackles from Burton and Luke Morahan in a manner that would have made Jonah Lomu proud, with his try putting the visitors right back in the contest.
Foley couldn't convert from out wide to draw the teams level and the Force noticeably lifted the tempo with the crowd getting behind them.
A monster rolling maul with forwards and backs involved proved to be unstoppable, with Hodgson the man at the bottom of the pile for his third try in three games.
Burton's missed conversion meant the Force only were ahead by a converted try heading into the final quarter to keep the Waratahs just about in touch.
Breaking down the rock-solid Force defence though was another matter, with the bottom side sniffing that elusive victory.
Hodgson's yellow card meant the Force would have to do it the hard way without their captain much to the frustration of the home fans after watching the replay on the big screen.
Forcing a turnover from the maul and then winning a scrum penalty lifted their hopes however as the Waratahs execution let them down once more with time running out.
With the pressure on, the Waratahs' errors kept coming and poor passes put them on the back foot, as the Force then won a penalty from the scrum to kill off the game.
By slowing the game down and more than matching the Waratahs physically, the Force completed a memorable double over the Super Rugby champions for only their second win of the year.
It wasn't pretty, but no one in Perth will care.
Tries: Louwrens, Hodgson
Pens: Burton 2
Yellow Card: Hodgson
Pens: Foley 2
Yellow Card: Kepu
Force: 15 Luke Morahan, 14 Marcel Brache, 13 Kyle Godwin, 12 Solomoni Rasolea, 11 Nick Cummins, 10 Sias Ebersohn, 9 Ryan Louwrens, 8 Ben McCalman, 7 Matt Hodgson (c), 6 Angus Cottrell, 5 Adam Coleman, 4 Steve Mafi, 3 Tetera Faulkner, 2 Nathan Charles, 1 Pekahou Cowan
Replacements: 16 Heath Tessmann, 17 Chris Heiberg, 18 Guy Millar, 19 Wilhelm Steenkamp, 20 Kane Koteka, 21 Alby Mathewson, 22 Luke Burton, 23 Mitchell Scott
Waratahs: 15 Israel Folau, 14 Taqele Naiyaravoro, 13 Adam Ashley-Cooper, 12 Kurtley Beale, 11 Rob Horne, 10 Bernard Foley, 9 Nick Phipps, 8 Wycliff Palu, 7 Michael Hooper, 6 Jacques Potgieter, 5 Dave Dennis (c), 4 Will Skelton, 3 Sekope Kepu, 2 Tolu Latu, 1 Benn Robinson.
Replacements: 16 Hugh Roach, 17 Jeremy Tilse, 18 Paddy Ryan, 19 Mitchell Chapman, 20 Tala Gray, 21 Pat McCutcheon, 22 Brendan McKibbin, 23 Matt Carraro
Referee: Rohan Hoffmann
Assistant Referees: Andrew Lees, Matt O'Brien
TMO: Peter Marshall