Douglas B won the big match in the Shimmin Wilson Manx Shield on Saturday.
They triumphed 28-19 at Vagabonds B in the first of their battles.
They face each other again in a fortnight.
The fast-improving Emerging Nomads saw off Castletown 36-20.
Jimmy Cubbon (two), Gareth Walt, Nick Morby, Dave Horan and Gerrard Landells grabbed the Nomads tries.
Dave Edge (two) and Pat Gandy added conversions.
For Castletown, Billy Harban and Barry Irvine notched tries with Sam Peel kicking two conversions and two penalties.
Athletics: Island competitors take on Manchester Half Marathon
Enduro: Hitchen claims impressive silver in Scotland
Hockey: IoM Men's Over-35's take debut victory
Athletics: Dan Richmond wins inaugural Backyard Ultra Isle of Man