Royals lead the win tally 3-1 this season but Eagles coach Dan Atkins believes if Tuggeranong repeat their performance on Saturday, the premiership will be there's to lose.
"It's a cliche saying but the better team won on the day and they really proved why they are the minor premiers," Atkins said.
"We were on the back foot early and playing catch up from there, they were very good and we just couldn't match it with them in the end.
"They'll be a tough team to beat next week, the Royals will have job cut out for them and if Tuggeranong play like they did today, Royals will find it hard."
Tuggeranong coach Nick Scrivener said he was pleased to see his men bounce against the Eagles but emphasised the job isn't finish.
"It was a good response and I'm very pleased but it's a big day next week with all our grades in, which is a fantastic effort," Scrivener said.
"The aim is to play your best in the biggest game, we were a little bit off last week so it was a good response with our intensity and I thought we defended really well.
"It's a grand final now and hopefully we can put on our best and hopefully our best is good enough. Royals are a good side and showed that last week.
"The [rivalry] goes back a long time but we’ve just got to turn up and do our best. We’re certainly not assuming anything."
The teams were battling high winds and rain on Saturday but it was the Vikings who shot out of the blokes and dominated from the opening whistle.
Gungahlin hardly touched the ball in the opening exchanges as Tuggeranong scored three tries in the first 28 minutes, but the visitors pulled one back to trail 19-7 at the break.
Australian under-20 prop Tom Ross backed up a full game in colts with a 40-minute effort for the Eagles but the Vikings ran away with it in the second stanza.