Aston Villa beat Midlands rivals West Bromwich Albion 4-3 on penalties to reach the Championship playoff final on Tuesday (May 14) after the tie ended 2-2 on aggregate.
Leeds United and Derby are in the other playoff semi-final.
West Brom was without suspended star striker Dwight Gayle but got a goal from Craig Dawson in the 29th minute to draw level.
Villa kept momentum, but Johnstone plucked out Adomah's header from the post four minutes later, as the match went to a penalty shoot-out.
Conor Hourihane, Mile Jedinak, Jack Grealish and Tammy Abraham all scored their spot-kicks for Villa with the only miss coming from Albert Adomah, taking fourth, who blazed his penalty over the crossbar. "All of us are very hungry".
Chris Brunt's red card in the 80th minute saw West Brom play 40 minutes with 10 men, but the club managed to hold on to force the shootout.
The hosts held out manfully during extra-time, but Villa goalkeeper Jed Steer saved West Brom's first two penalties of the shootout from Mason Holgate and Ahmed Hegazi. "We practice penalties, so I think I must've faced a 100 a day the last few days".
They will face Leeds or Derby, who meet at Elland Road for their second leg on Wednesday night, with Leeds leading 1-0 on aggregate.
The Championship playoff final is regarded as the most lucrative match in world soccer with last year's clash between Fulham and Villa worth about 170 million pounds ($219.44 million) even if, as in Fulham's case, the victor is relegated after one season in the top flight.
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