Bolton Wanderers squandered a two-goal lead to leave themselves in the relegation zone ahead of the Premier League's final day.
Both sides had chances in an end-to-end opening 20 minutes but it was West Brom who came closest when Shane Long spun at the near post and fired at Adam Bogdan, who could only palm onto the upright.
The Trotters went ahead in the 24th minute when Martin Petrov beat Ben Foster from the spot after Keith Andrews was adjudged to have brought down Mark Davies.
After the interval Graham Dorrans spurned a chance to level proceedings when he was found space on the penalty spot and tamely hit his effort into the gloves of Bogdan.
Kevin Davies then almost made it two when he headed towards the corner but was denied by Foster.
Owen Coyle's men did double their advantage moments later through a huge slice of luck. Petrov's centre seemed to have caused no harm until Liam Ridgewell's clearance ricocheted off Billy Jones's back past Foster into the net.
West Brom pulled one back within minutes when Chris Brunt slid home a loose ball to set up a tense final 15 minutes.
Bolton went on to the back foot, looking to defend their lead and Bogdan saved from Simon Cox before the worst possible scenario for the Trotters' fans.
First Djibril Cisse put relegation rivals QPR ahead against Stoke and then James Morrison equalised for West Brom by turning home at the back post.
A point for Bolton means they are now two points adrift of safety. They travel to Stoke on the final day while QPR go to league leaders Manchester City.
Pascal Lemesre
