Javi Gracia thought all was lost before his Watford side came from two down to beat Wolves 3-2 and reach their first FA Cup final since 1984.
Substitute Gerard Deulofeu scored twice as the Hornets – 2-0 down with 11 minutes left – won in extra-time to secure a meeting with Manchester City.
Matt Doherty’s header and a volley by striker Raul Jimenez had put Wolves in control before Deulofeu scored with a clean chip. Captain Troy Deeney also scored with a stoppage-time penalty to send the game to extra-time, and Deulofeu then won it with another fine finish.
Watford goalkeeper Heurelho Gomes was emotional after the win. The 38-year-old – who was in tears at the end of their quarter-final win over Crystal Palace in March – has plans for retirement at the end of the season and could now end his career with an appearance in the final.