Onchan surprised Ayre United in the GH Corlett Woods Cup preliminary round.
Craig Marsh, Mark Burman, Gerard Colligon and Mark Rees were on target in a 4-2 home win.
Phil Quayle and Elliot Cureton replied for the Tangerines.
Douglas Athletic are up to fifth in JCK Division Two after an 8-1 thrashing of Braddan.
A Josh Green treble, a Liam Dawson double and further goals from Darren Shields, Andy Newton and Stuart Monks (penalty) secured the three points to lift them above Colby in the table.
Shooting: Winter series gets underway
Ward, Berg and Parr lead the way
Cycling: Bostock nominated for national champion of the year
Manxman one of six riders on British Cycling shortlist
Football: Railway Cup hopefuls all maintain pace in premier league
Castletown stay four points clear atop Division 2
Rugby: Vagabonds Ladies stay top with another victory
Vagabonds men and Douglas also take respective wins on home soil