IT may have just beaten the top side but Purnim knows an even bigger test awaits it in next week's semi-final.
Standing in the way of a grand final berth is the Panmure Bulldogs, which showed it is ready for a serious tilt at a fifth premiership in a row with a successful run chase against Wangoom.
Purnim consigned Yambuk to just its second loss of the season as its bowlers put in their tightest and most consistent effort of the year, according to captain-coach Shaun Griffin.
He will be hoping his bowlers again do the job next week, knowing the ability of the Bulldogs' batting line-up to destroy wayward attacks.
"It is good to win against the top side, it does give us a bit more confidence but it is a different ball game now we're in the finals," Griffin said yesterday.
"Panmure Bulldogs has won the last four flags ? they are obviously the team to beat at this time of year ? but we are looking forward to it and it should be a good contest."
Griffin said his attack could be boosted by the return of Isaac Richardson, who will test his fitness this week after a month on the sidelines due to a dislocated shoulder.
Chasing Purnim's 193, Yambuk's steady but slow start was rocked by the loss of captain Steven Gleeson, who was forced to retire hurt on 12.
Fellow opener Sean Peterson laid the foundation with 52, before Greg Bull (3-42 from 20.3 overs) grabbed the first of his big scalps to leave Yambuk at 3-96.
With more than 400 runs this season, Geoff Blackmore now held the key but Bull drew his edge on 31 to help clinch victory, Yambuk falling short by 19 runs.
The experienced Panmure Bulldogs fine-tuned for the finals with a strong win over Wangoom.
The Bulldogs defied injury concerns and an ultra-competitive target of 262 to deny the cellar dwellers their second win of the season, finishing at 9-273.
Openers Tim Bryce and Sean James set about the run chase in great fashion, adding 66 for the first wicket before James departed for 33.
Bryce compiled 73, including three sixes and five boundaries, before Paul Rea (77) and Simon Bourke (33no) saw the Bulldogs home.
With James McKinnon and Daniel Meade on the sidelines, the Bulldogs highlighted their depth.
Panmure's other team, the Pups, clinched their first finals berth with a comfortable win over Killarney.
The winner of the clash had the incentive of grabbing fourth spot, but a disappointing effort with the bat from the Crabs ensured the match didn't live up to its billing.
Resuming on Saturday 12 runs ahead at 4-119, the Pups continued until they reached 6-171, when the game was called off early.
Bruce Buck has struck form at the right end of the year, posting an unbeaten 53, combining with Simon Schrama (42) to see his side book a semi-final against league leader Yambuk.
Liam Cole was the best of the Killarney bowlers with 3-45.
In the B grade, Yambuk escaped in a thriller against Panmure to send the Bulldogs crashing out of finals contention.
Defending just 95, a hat-trick from Craig Buchanan (3-12) helped Yambuk restrict Panmure to just 90.
A big win over Woolsthorpe helped Wangoom grab fourth spot, while Purnim will take a lot of confidence into its semi-final appointment with Mailors Flat after a 118-run win, thanks to a five-wicket haul from Greg Billington.