Millwall reached the Sky Bet League One play-off final on Friday after a 1-1 draw at home to Bradford meant they progressed to face Barnsley at Wembley with a 4-2 aggregate win.
Only three sides in play-off history have overturned more than a one-goal deficit from the first leg to reach the final - one of those teams was Bradford in 1996, against Blackpool, but the Bantams' hopes of a turnaround were dealt an early blow at The Den when Lee Gregory fired home for the hosts, who had won 3-1 at Valley Parade last Sunday.
Bradford did reduce the deficit back to two goals just before the break through Jamie Proctor, but they never really looked capable of staging a fightback.
Millwall will now face the Tykes, who beat Walsall 6-1 on aggregate in the other semi-final, at Wembley on Sunday May 29 for a place in the Championship.
Bradford had never won at The Den in seven attempts and almost made their task an impossible one inside two minutes.
A mix up at the back saw Steve Morison hook a ball over the top for Gregory to chase, but goalkeeper Ben Williams raced off his line to just about thump the ball clear.
Bradford midfielder Josh Cullen made a brave and crucial block on 16 minutes from Ben Thompson, who had burst through on goal, as Millwall continued on the front foot.
Bradford scored just 55 goals in League One this season - 18 teams scored more - and they struggled to force the issue at The Den, allowing Millwall to dictate the tempo of the game, which looked a dangerous ploy.
They were punished for their lacklustre approach on 34 minutes.
Morison held the ball up impeccably well before teeing up his strike partner Gregory, who found the bottom corner with a cool finish from 18 yards - his 27th goal in all competitions this season.
Just as Bradford looked down and out, they struck out of the blue just before half-time.
Kyle Reid inserted some pace into Bradford's attack and charged down the left flank. His cross was met by Proctor, who needed two bites at the cherry but managed to steer the ball home at the second attempt.
The deficit was back to two goals but it could have been even closer before half-time, had Proctor not taken far too long to get his shot away when through one-on-one.
Millwall's Byron Webster headed just wide on 54 minutes from a Shane Ferguson corner as Bradford failed to build on their intense end to the first half.
Despite throwing three men into attack, Phil Parkinson's men lacked any creative spark to force home goalkeeper Jordan Archer into any sort of action.
The final whistle sounded and Millwall fans raced onto the pitch to celebrate their triumph. They head to Wembley looking to gain promotion for just the second time through the play-offs on their seventh attempt.