The midfielder netted the winning spot kick after his goalkeeper had denied Marc Muniesa to give Jurgen Klopp the chance to claim his first silverware at Anfield.
Allen netted to give the Reds a 6-5 victory from the spot after Marko Arnautovic’s goal – scored from an offside position – had levelled the tie at 1-1 on aggregate, with no further goals separating the two sides over 120 minutes.
Peter Crouch, Emre Can and, crucially, Marc Muniesa missed from the spot in a seven-round shootout, with Simon Mignolet denying the Spanish defender to set Allen up to win it.
Liverpool will face either Everton or Manchester City, who meet at the Etihad Stadium on Wednesday night, on February 28.
~Goal.com