For not the first time this season, the competition leader struck virtually from the first whistle, after a switch play set left fullback Craig Ferguson free.
Ferguson flew up the left wing and delivered a cross which Michael Hogan swept past keeper Liam Whittaker.
After a pre-match talk urging his side to produce a tight beginning, Mosgiel coach Andrew Brook held his head in his hands following the early setback.
Mosgiel retaliated with a carving run from Cody Brook and a shot that tested Caversham keeper Liam Little.
However, the home side's defence was ragged and rarely looked compact, and it came as no surprise when centreback Ben Fitzpatrick stabbed in another goal to give Caversham a 2-0 lead after just 11 minutes.
Caversham's opponents have often wilted under such relentless pressure, but Mosgiel, willed on by a large crowd, clawed its way back in to the match.
Striker Regan Coldicott always looked capable of out-running Caversham's defence.
He had several clear chances to score but failed to hit the target.
Chilean Eder Franchini steadied the home side's midfield, sliding some penetrative passes through gaps for Brook and Coldicott to run on to.
It was former Roslyn and Hawke's Bay player Harley Rodeka who provided Mosgiel's only goal.
He accelerated from deep and laced a strong shot into Caversham's goalpost, before cracking in the rebound for a memorable goal that narrowed the gap to 2-1.
Caversham strikers Lewis Jackson and Tore Waechter continually caused headaches for Mosgiel, and only a fine match by Whittaker, who pulled off several point-blank saves, kept Caversham at bay.
Both sides were forced to dig deep in the second half as wintry rain and wind made passing and ball control difficult.
Sam Cosgrave hurled some giant throws into the Mosgiel goal mouth and, although the home side's Cam McPhail had a steady match, Caversham put more heat on the ball as Andrew Ridden, Waechter and Fitzpatrick combined skill and aggression.
Fitzpatrick scored the goal of the match 13 minutes in to the second half.
He peeled away from Whittaker after a set-play and twisted in mid-air to bullet a header under the Mosgiel crossbar and give his side a 3-1 lead.
Mosgiel rallied but was not able to narrow the gap. In other matches, Dunedin Technical jumped to equal third on the ladder with Mosgiel, after beating bottom side Green Island 3-0 at Sunnyvale, while Northern beat University 5-3.
