Rangi Chase kicked a dramatic golden-point drop goal as Salford Red Devils knocked out last year's beaten finalists Hull FC in the Challenge Cup.
Joe Arundel opened the Hull scoring, as Francis Meli and Chase replied, before Arundel grabbed his second.
Meli doubled his score, only for Jamie Shaul (2), Fetuli Talanoa and Jordan Rankin to put the hosts back in front, with Theo Fages adding one for Salford.
Junior Sa'u and a last-gasp Meli score levelled it up before Chase's heroics.
It was a thrilling finish to a game that was far more competitive than Hull's 30-8 win over the same side a week ago in Super League.
Salford owner Marwan Koukash had demanded an improvement from his team, which came, but not until they were trailing by 10 points midway through the second half.
In an error-strewn game, the Black and Whites looked to be advancing to the fifth round when Jordan Rankin coasted through a non-existent Red Devils backline on 53 minutes to put the hosts 28-18 up.
But Salford stayed in touch and Meli completed his hat-trick with only 66 seconds left on the clock to take it into extra time.
With the first score deciding the winner, Chase popped his kick between the posts from open play with just two minutes of the added period remaining.
Hull FC: Shaul, Arundel, Crooks, Yeaman, Talanoa, Rankin, Miller, Paea, Houghton ,Bowden, Tuson, Hadley, Westerman
Replacements: Watts, Heremaia ,Paleaaesina, Thompson
Salford Red Devils: Mullaney, Johnson, Gleeson, Sa'u, Meli, Chase, Smith, Morley, Lee, Tasi, Hansen, Hock, Rapira
Replacements: Fages, Puletua, Walne, McPherson
Referee: Ben Thaler