Leeds still were well set to defend the attack but Welbeck out-paced and out-muscled the hapless Diego Llorente before dinking an excellent finish over Illan Meslier.
Raphinha snatched at a half-opening early in the second period and Jack Harrison blazed over.
Robert Sanchez produced a flying save to keep out Raphinha’s thumping drive from a free-kick and the Brazilian then turned Rodrigo’s arcing low cross just the wrong side of a post as Leeds gave Elland Road plenty to cheer.
However, with time running out, the home fans sensed it was not to be their day and a section turned on the club’s hierarchy.
A chorus of “sack the board” rang out as Welbeck missed a golden chance to seal victory for the Seagulls in the closing stages by heading Leandro Trossard’s cross wide.
But in the second minute of added time, Gelhardt evaded several challenges in Brighton’s box and crossed to the far post where Struijk rose to head home a vital equaliser.
Leeds have hope going into the final day.
However, at White Hart lane Harry Kane’s penalty goal moved Tottenham into the Premier League top four as Antonio Conte’s men struggled to defeat relegation battlers Burnley.
Spurs are now two points clear of Arsenal who have a date with Newcastle on Monday night to seek a return to top four.
Tottenham still need a slip up from the Gunners to return to the Champions League next season, but upped the pressure on Mikel Arteta’s men.
Burnley are only still in the fight for their place in the top flight thanks to a run of 10 points from a possible 12 in the first four games after sacking Sean Dyche.
Defeat at home to Aston Villa last weekend ended that unbeaten run, but there was plenty of encouragement for the Clarets they can do enough to survive in the final week of the season.