Oxford United reached the Johnstone's Paint Trophy final despite losing the second leg of their southern area final at home against Millwall.
Lee Gregory's second-half strike gave Neil Harris' side victory on the night at the Kassam Stadium.
But the Lions were unable to turn around a 2-0 deficit from the first leg and had Mark Beevers sent off for a second yellow card on the hour mark.
Oxford will face either Fleetwood or Barnsley in a Wembley final on 3 April.
Michael Appleton's side had the cushion of two Kemar Roofe goals from last month's first leg at the New Den.
Millwall went close early on when Steve Morison headed Shane Ferguson's cross over the bar, Liam Sercombe sent a dipping volley just wide for the hosts while Jed Wallace forced U's keeper Benji Buchel into a low save to his left.
Gregory finished a neat move after good work from Aiden O'Brien to give Millwall hope, but centre-half Beevers was given his marching orders after bringing down Danny Hylton.
Callum O'Dowda nearly punished Millwall further but his curling free-kick was superbly tipped wide by keeper Jordan Archer.
- 11MacDonaldSubstituted forBoweryat 81'minutes
- 15O'DowdaSubstituted forIsmailat 89'minutes
- 2CummingsBooked at 59minsSubstituted forMartinat 68'minutes
- 16BeeversBooked at 65mins
- 8UpsonSubstituted forOnyedinmaat 82'minutes
- Scott Duncan
- Shots on Target