West Yorkshire club Bradford defied the odds to reach the Capital One Cup final two years ago with famous wins against Arsenal and Aston Villa along the way - and in their latest cup outing they swept aside the Londoners, who never recovered from the early dismissal of defender Mark Beevers.
Ian Holloway's side were reduced to 10 men in the sixth minute, found themselves 3-0 down at half-time following goals from James Hanson, Jon Stead and Andy Halliday and conceded a fourth when Billy Knott struck early in the second period.
Nobody among the 11,859 crowd was allowed to catch breath in a frenetic opening 45 minutes, which also saw both Bradford manager Phil Parkinson and assistant Steve Parkin sent to the stands for their part in a mass melee.
Beevers was shown a straight card by referee James Adcock for hauling down Bradford striker Hanson, who would otherwise have been clean through on goal as he ran on to defender Rory McArdle's excellent pass.
Millwall were made to pay within two minutes
McArdle flicked on Halliday's corner and Hanson headed home at the far post into the top corner.
The Londoners were dealt another hammer blow with the first half barely 17 minutes old
Bradford winger Filipe Morais swung over a free-kick from the left and Stead pounced on fit-again Andrew Davies' knockdown to side-foot a low left-footed shot beyond Millwall goalkeeper David Forde.
Forde was lucky not to follow Beevers down the tunnel soon after when the game threatened to combust.
Millwall defender Alan Dunne's full-blooded challenge sent Hanson clattering into the advertising boards and triggered a furious exchange between players from both sides, with Forde, who had charged from his area, Parkinson and Parkin all in the thick of it.
Dunne, Forde and Bradford midfielder Billy Knott were all booked for their part, while referee Adcock promptly marched to the home dugout and ordered Parkinson and Parkin to the stands.
Bradford delivered the knockout punch following a sweeping move in the 39th minute when Knott sent Morais clear down the right and Halliday slammed home the Portuguese's fine cross at the far post.
Bradford went straight on the offensive after the break and added to their tally through Knott, who forced the ball home from close range after defender James Meredith's shot had been blocked.
Home substitute Francois Zoko hit the post with a left-footed effort in the 73rd minute and Bradford fans sang 'Bring on the Chelsea'.
For Millwall, third bottom in the table with two wins now from 22 matches in all competitions, it was a night to forget in a wretched season.
Substitute Magaye Gueye's bobbling 86th-minute shot was their first effort on target all evening and it was all a far cry from their own memorable FA Cup run two years ago when they reached the semi-finals.
Source : PA