Rugby league convert Zac Lomax was a late withdrawal from what would have been his Super Rugby Pacific debut with a tight hamstring but his Western Force teammates managed to stun the Reds 42-19 without him in Brisbane on Saturday.
Argentina lock Franco Molina scored a hat-trick as the Perth-based side notched up a second win of the season to deny the Reds the chance to move above the Brumbies into third place in the standings at the end of round eight.
Hurricanes and Blues, who top the table on 25 points, had byesand the Chiefs leapfrogged the Brumbies and the Reds with a 42-14 victory over the New South Wales Waratahs to sit three points behind them.
Winger Kyren Taumoefolau and centre Quinn Tupaea scored two tries apiece in Hamilton as the Chiefs brushed aside their Australian visitors earlier on Saturday.
Taumoefolau chased down scrumhalf Xavier Roe's kick to give the Chiefs a ninth-minute lead and hooker Samisoni Taukei'aho extended it before fullback Sid Harvey scored his first Super Rugby try to keep the Waratahs in touch.
Centre Tupaea restored the home side's advantage and Josh Jacomb ensured the hosts held a 16-point lead at the interval with his second penalty.
Tupaea muscled over seven minutes after the break before flanker Samipeni Finau drove through the defence for his side's fifth try. Pete Samu hit back for the Waratahs but Taumoefolau burst clear from inside his own half to seal the victory.
In Brisbane, flyhalf Ben Donaldson pulled the strings as the Force took a 21-12 lead at halftime after Molina's two scores from close range and a third try from a dazzling display of inter-passing that was finished off by fullback Mac Grealy.
Winger Darby Lancaster soared to catch a Donaldson crosskick for the fourth before hooker Brandon Paenga-Amosa went over from close range to leave his former team trailing 35-12 with Harry Wilson in the sin bin.
Reds winger Filipo Daugunu finished off an 80-metre move five minutes from time to keep home hopes alive, but Molina powered over for his third score to seal the Force's first win at Lang Park since 2017.
In Friday's match, the Crusaders paid an emotional farewell to their temporary home of the last decade before their move to a new stadium with a resounding 69-26 thrashing of the Fijian Drua.
Codie Taylor scored four tries in his 150th Super Rugby match as the 13-time champions ran in 11 five-pointers in front of a sell-out crowd in Christchurch to move up to fifth in the standings.
Wingers Sevu Reece and Chay Fihaki both scored twice with flanker Corey Kellow and replacement prop Seb Calder also getting on the scoresheet for Rob Penney's side.