Four minutes of play-off euphoria was all West Brom fans were able to savour as their promotion dream died in south Wales.
For a very brief window midway through the first-half, the Baggies moved into sixth place in the table but their own defensive frailties, and the efforts of Millwall and Sunderland, meant the fantasy did not last long.
It was finally extinguished for good when Swansea's Dutch striker Joel Piroe struck a magnificent low free-kick into the far corner for the injury time winner.
It was Piroe's 20th goal of the season in all competitions and 19th in the Championship.