Partick Thistle recorded their biggest-ever victory over Airdrie as Chris Erskine bagged a brace to help send the Glasgow side back to the top of Division One.
Erskine steered his left-footed shot past former Thistle goalkeeper Kenny Arthur after four minutes to open the scoring, ending the midfielder's seven-game goalless run.
The 25-year-old was upended by Alan Cook inside the box seven minutes later and Aaron Muirhead scored his second penalty of the season.
Steven Lawless found the back of the net with a low shot after half an hour.
A sweeping 42nd-minute move ended with Sean Welsh tucking away Stephen O'Donnell's cross.
The Jags' remarkable first-half performance was capped by Erskine notching his second on the stroke of half-time, coolly slotting the ball past Arthur.
Kris Doolan got in on the act in the 57th minute, applying the finish to O'Donnell's assist.
Diamonds substitute Scott Sally had been dismissed for a foul on Muirhead after 76 minutes.
Four minutes later, Ross Forbes struck a free-kick into the bottom corner as Thistle went two points clear at the top after Dunfermline Athletic were held to a 2-2 draw at home to Morton.
Partick Thistle: Fox, Stephen O'Donnell, Muirhead, Balatoni, Bannigan, Lawless (Elliot 66), Paton, Forbes, Welsh, Craig (Doolan 46), Erskine (Slane 66). Subs Not Used: Scully, Sinclair.
Goals: Erskine 4, Muirhead 11 pen, Lawless 30, Welsh 42, Erskine 45, Doolan 57,Forbes 80.
Airdrie Utd: Arthur, Hart, Lilley, Stallard, Cook (Evans 47), Bain (McLaren 54), Buchanan, Blockley, Josh Watt, Jack Boyle, Donnelly (Sally 65). Subs Not Used: Duncan, Griffin.
Sent Off: Sally (76).
Ref: Euan Norris