Albury Thunder turned on the razzle-dazzle in smashing Cootamundra 66-6 on Sunday.
"I gave the boys the opportunity to take the shackles off a little bit," he said.
"We've probably been playing a bit too one-out, a bit predictable.
"Leading into finals we know we're going to have to move other teams around and play with a bit of flair.
"I think the boys showed what they're capable of and we've just got to improve on that next week."
Hard-running centre Etu Uaisele and powerful back-rower Liam Wiscombe scored doubles, along with winger Curtly Jenkinson, who was playing his 100th game.
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Fellow flanker Keanau Wighton finished with 22 points from a try and nine goals.
Thunder looked like keeping the Bulldogs scoreless, but hooker James Woolford barged across with seven minutes left.
"We spoke about moving the ball around out of yardage, which took a bit of juice out of them," Purtell said.
"Obviously Cootamundra's struggling a little bit this year, we couldn't focus on that, we could only focus on us.
"We had a real focus of trying to keep them to zero, defensively we were really impressive, but we've still got a lot we can work on for next week."
Long-time Riverina rugby league supporters are saddened by the fall of Cootamundra, which was a nursery for the sport, producing former superstar Les Boyd in the 1970s, as well as a number of other classy NRL first graders.
The Bulldogs remain winless after 16 rounds.
This weekend, round 17 of the Group Nine competition, Cootamundra Bulldogs host seventh-placed Temora Dragons ahead of the following weekend's final regular round against the Young Cherrypickers.