Glenrothes made a remarkable recovery to take the spoils from Wednesday night's derby game in Memorial Park.
The Hibs led through Daniel McNab in the 15th minute and when Chris Ireland headed the second ten minutes later it looked like a case of how many goals they'd win by.
However just two minutes later, Scott Napier smashed the ball home after capitalising on slack play. This strike gave the visitors a lift and only a goal-line clearance from Stuart Drummond prevented Jamie Leslie from claiming an equaliser.
However by the 32nd minute, it was all-square when Gavin Moffat headed home Callum Kinness' free-kick Glenrothes went ahead in the 53rd minute when Napier netted his second with a terrific shot on the turn and then well-struck free-kicks from Sean Simpson in the 72nd and 82nd minutes effectively killed the game.
Thornton's day went from bad to worse when Chris Ireland and Ian Shanks were both red-carded in separate incidents. Max Coleman had the last word after scoring from close range in stoppage time but by that time the damage had been done.
Thornton Hibs: Clark, M.Robertson, McMillan, S.Drummond, Shanks, Adam, McNab, Hepburn, Ireland, Thomson, Anthony. Subs: Crichton, Shields, A.Drummond, Coleman, Hoskisson, Wilson.
Glenrothes: Gear, Kinness, Anderson, Pearson, Moffat, McDonald, King, Napier, Celentano, Schiavone, Leslie. Subs: Simpson, Wallace, Sneddon, Campbell, Small.
Referee: Mr C.McNab