Christian Benteke's last-gasp penalty clinched a crucial 2-1 win for Aston Villa over West Brom as they escaped the relegation zone.
The striker scored in the fourth minute of injury time after Ben Foster had brought down Matt Lowton to cap a dramatic derby.
It was Villa's first league win since December - and Tim Sherwood's first as boss - and ended a seven-game losing streak.
Saido Berahino looked to have earned a point for below par West Brom after he cancelled out Gabby Agbonlahor's opener, but Villa deserved the win and could have been clear by half time after Fabian Delph hit the post and Agbonlahor had two efforts cleared off the line.
It moved them three points clear of the Premier League drop zone as West Brom remained 13th.
Albion survived a huge let off after 16 minutes when Agbonlahor collected a cross, spun and fired at Foster.
It looked a straightforward one for the goalkeeper, but he let it slip through his fingers and the ball trickled goalwards. Foster recovered to claw the ball back off the line as goal-line technology ruled it had not gone over.
Villa had their tails up and grabbed a crucial lead on 22 minutes when Agbonlahor took first blood in his personal duel with Foster.
Sherwood had urged his new side to find Benteke early and Brad Guzan's long clearance went straight to the striker, who flicked the ball on for Agbonlahor.
The forward then outpaced Joleon Lescott and slipped the ball under the advancing Foster for just his fourth goal of the season and first since November.
It was the first goal Albion had conceded in 440 minutes.
Albion levelled on 66 minutes when Chris Brunt's deep corner was headed back by Lescott and Berahino was left alone in the six yard box to nod in his 18th, and simplest, goal of the season.
Villa Park almost boiled over when Berahino and Alan Hutton squared up with the latter landing a nasty challenge on the frontman. The Scot was lucky to escape from with just a booking.
There was a further twist in injury time though when Foster took down Lowton in the box and Benteke sent him the wrong way from the spot.
Aston Villa: Guzan, Lowton, Okore, Clark, Hutton, Cleverley, Westwood, Delph, Agbonlahor, Benteke, N'Zogbia. Subs: Bacuna, Sinclair, Weimann, Sanchez, Gil, Given, Grealish.
West Brom: Foster, Dawson, McAuley, Lescott, Brunt, Fletcher, Yacob, Gardner, Morrison, Berahino, Ideye. Subs: Wisdom, Olsson, Baird, Myhill, Pocognoli, Mulumbu, Sessegnon
Man of the match: Gabby Agbonlahor
Match rating: 6/10
Referee: Jonathan Moss (W Yorkshire)