Going into the clash having lost six of their past eight games, the Brumbies needed a victory at GIO Stadium on Saturday to cement their position inside Super Rugby Pacific's top six.
Captain and halfback Lonergan was instrumental in achieving that, scoring a try, nailing two crucial penalty goals and registering 69 passes to help his side (29 points) leapfrog the Queensland Reds (27 points) into fifth, with only two games remaining for the team.
It wasn't smooth sailing as the teams tussled for possession and dominance, despite a fast start for the hosts when young gun Lachie Shaw crashed over inside two minutes.
Leading 14-10 at halftime, Lonergan edged the Brumbies further ahead when he slotted a penalty goal before scuttling over the line in the 53rd minute off a pass from his brother Lachlan to lay the platform for victory.
Wallabies flanker Carlo Tizzano crossed to keep the visitors in the contest, before Lonergan kicked another penalty goal and local product Chris Mickelson sealed the game with a try in his Super Rugby debut.
"Last year was the breakthrough season for him (Lonergan) ... But I genuinely feel he's playing better this year than he did last year," Brumbies coach Stephen Larkham said.
"Ryan's composure in and around the leadership and how he speaks to the boys is just putting everyone in a really good position to perform."
The Force badly needed a win to stay in the finals conversation, but despite the result, coach Simon Cron still believes his side can play in the post-season, although they are nine points adrift of the Reds.
They will also count the cost of losing scrumhalf Henry Robertson who was helped off the field with a knee injury in the first half.
"We've got three games at home ... We've got a job to do, so we've got to recoup, fix and get into it again," Cron said.
"They won the collision tonight, and we gave away quite a few penalties, which put us back in our 22 and kept the ball away."
It took just over a minute for the Brumbies to get on the scoreboard when Shaw picked up the ball from the ruck and scurried across the line.
The Force settled, and were rewarded when prop Harry Johnson crashed over, before Ollie Sapsford re-established the Brumbies' lead following a blistering run by fellow winger Corey Toole.
After halftime, Lonergan scored before Tizzano closed the deficit when he wrestled over for a five-pointer from a lineout maul.
But Mickelson fell over the line just moments after coming off the bench to ice the victory in the 75th minute.
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