Tim Cahill marked his return to match action with a goal as Millwall U23s saw off Coventry City in bitter conditions on Monday afternoon.
The forward, playing for the first time since joining The Lions as a free agent last week, swept home from close range to make it 2-1 after Kristian Brymora's early strike was cancelled out by Sky Blue striker Jonson Clarke-Harris.
The visitor's second goal capped off an eventful opening 45 minutes at Calmont Road. Kyle Reid met a looping cross at the far post and smashed a first-time effort in off the underside of the bar to draw the sides level.
Young Lions 'keeper Harry Girling was kept busy after the restart, punching away a number of dangerous deliveries before making a fine double-save to deny Clarke-Harris and keep City from pulling ahead.
The Professional Development League fixture seemed destined to end in a draw before Harry Donovan collected the ball in space in the 90th minute, drove to the edge of the area and drilled low beyond the reach of Corey Addai with virtually the last kick of the game.
Millwall: Harry Girling, Noah Chesmain, Harry Toffolo, Harry Donovan, Jesse Debrah, Christian Mbulu, Tim Cahill, Jethro Hanson, Kristian Brymora, David Ajiboye, Ben Marshall.
Subs: Junior Tiensia, Samuel Jackson, Mason Saunders-Henry, Isaac Oloafe, Noel Leighton.