Albion fell to a 2-1 defeat against Aston Villa in their Play-Off semi-final first leg at Villa Park.
Dwight Gayle's 24th goal of the season handed the Baggies a 16th-minute lead in a highly-charged encounter, coming after Jay Rodriguez had already seen his earlier effort rebound off the crossbar.
Yet midlands neighbours Villa hit back with two goals in four second-half minutes to take a slender advantage into Tuesday's second leg at The Hawthorns, although the Baggies will be without Gayle after the striker saw red late on following a second bookable offence.
Substitute Conor Hourihane levelled matters with a fierce drive in the 75th minute before Tammy Abraham added a second from the penalty spot shortly afterwards.
It leaves the Sky Bet Championship Play-Off finely poised heading into next week's 171st meeting between the two clubs in front of a sell-out home crowd.
Caretaker Head Coach Jimmy Shan made two changes from the final day of the regular season at Derby County, captain Chris Brunt and Matt Phillips coming in for Rekeem Harper and Jacob Murphy.
Glenn Whelan headed over an early opportunity for the hosts but it was Albion who came closest with 11 minutes on the clock as Rodriguez's curling effort was pushed on to the crossbar by Jed Steer.
Abraham volleyed over before the Baggies struck first in the semi-final encounter, Gayle capitalising on a mistake from Whelan to drive forward and drill the ball home from the edge of the penalty area.
Both sides wrestled for control after the breakthrough, with a high-tempo and open encounter flowing from end to end, albeit with neither keeper seriously called into action.
Tyrone Mings forced a solid save from Johnstone in injury time as the first half drew to a close, with Albion holding a lead.
Dawson, who sustained an injury just before the break, was unable to continue and replaced by Tyrone Mears at the interval.
Johnstone saved well with his feet to deny Abraham soon after the restart, as the fiercely-contested clash continued to entertain.
Jacob Murphy replaced Matt Phillips after 66 minutes, with Bartley sending a header back across goal and wide from Brunt's corner soon afterwards.
Yet the hosts pulled themselves level courtesy of sub Hourihane's drive from the edge of the box.
And it was the home side who led in the 79th minute as Abraham slotted home a penalty following Kieran Gibbs' challenge on Jack Grealish.
Referee Graham Scott showed Gayle a second yellow card in the 88th minute as Albion finished the closely-fought encounter with 10 men heading into Tuesday's eagerly-anticipated second leg.
Albion: Johnstone, Dawson (Mears 46), Bartley, Hegazi, Holgate, Johansen (Morrison 85), Brunt (c), Gibbs, Phillips (Murphy 66), Rodriguez, Gayle.
Subs: Bond, Townsend, Field, Montero.