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.
Final 2026 ARA Championship round beckons
2026 End to End Walk taking place today
Football: Corinthians go top of premier league as Peel stumble
Rugby: Douglas Celts begin Manx Shield title defence with a win
