Gretna hot-shot Kenny Deuchar grabbed a stunning hat-trick to sink his former club.
Deuchar took his season's tally to 28 and debut boy Chris Innes also netted before being stretchered off.
Gretna took just two minutes to go in front when David Bingham flicked into Deuchar's path and the big hit man drilled home.
Deuchar doubled the advantage after nine minutes when he raced on to James McQuilken's through ball and flicked past on-rushing keeper Scott Morrison before knocking into the empty net.
Gretna again went close in the 24th minute when Morrison brilliantly turned Gavin Skelton's curling shot around the post.
New boy David Graham, a record £50,000 signing from Stranrar, replaced full-back Mark Birch in the 54th minute, and with his first touch smashed a 20-yard shot off the East Fife cross bar.
Morrison was called into action again two minutes later when he parried Bingham's shot and recovered to beat away Deuchar's close-range header from the rebound.
East Fife's Brian Fairbairn forced Gretna keeper David Mathieson into his only save of the game when he let fly from the edge of the box in the 67th minute.
Gretna made it 3-0 in the 79th minute when Innes, signed from Dundee United on Friday, rose to head in a Skelton corner at the far post.
But he was carried off with a badly gashed leg five minutes later after a tough 50-50 challenge with Brian Fairbairn.
Deuchar leapt to meet a Tosh cross and looped in his header for number four with five minutes to play.