Brighton sealed the upset in the 58th minute when Pascal Gross headed the ball just over the line to spark wild scenes at the Amex Stadium.
While second-placed United were wasteful, the Seagulls held their own with Ryan once again rock solid between the sticks.
The Aussie made three saves throughout the night and an earned a rating of 7/10 by The Mirror who described his overall performance as 'spot on'.
After a shaky start, Ryan has had a stellar first season in the Premier League putting a rocky stint at Valencia behind him as he's become Brighton's undisputed number one.
Brighton's win moves them up to 11th on the table, eight points clear of the relegation zone with two games to play.