Brett Ormerod was the toast of Southampton as he scored one goal and set up the other to earn Gordon Strachan's team an FA Cup final showdown with Arsenal.
The 26-year-old has spent the season in the shadow of his prolific 22-goal strike partner James Beattie, but he emerged after 43 minutes of the Villa Park semi-final to head home the most important goal of his career.
Ormerod had not scored since October 27th, but was in the right place at the right time to head home his seventh goal of the season from Chris Marsden's precise cross from the left.
Watford - who went into this semi-final without having conceded a goal in this season's competition - battled bravely, but their dreams were finally ended by Paul Robinson's own goal in the 79th minute.
Ray Lewington's men ensured a rousing finale and gave their fans some consolation when Marcus Gayle - the former Wimbledon striker who is now a centre-half - pulled a goal back with a header from Neal Ardley's corner with three minutes remaining.
The result meant the Saints can look forward to marching into Cardiff's Millennium Stadium on May 17 for their first FA Cup final appearance since 1976, when Bobby Stokes famously scored the goal which caused a major upset as the team managed by Lawrie McMenemy defeated mighty Manchester United.
It also means Southampton can look forward to European football next season, as the fact that Arsenal are destined to finish in the top four and secure a Champions League place will hand them a UEFA Cup spot.
The atmosphere was everything you could ask of an FA Cup semi-final from two sets of fans noted for their family values.
The Holte End it was a sea of Watford yellow, while the North Stand was awash with the red and white stripes of the Saints.
Ormerod's opener arrived after 43 minutes when Anders Svensson won possession in midfield and fed skipper Chris Marsden on the left flank. His cross was an inviting one and Ormerod was unchallenged on the six-yard line as he met it with a powerful header which Chamberlain could only help into his net to spoil the goalkeeper's 750th club career appearance.
Saints might have finished off Watford in the second minute of the second half. Beattie crossed from the left and Michael Svensson had more time than he realised as he headed the ball straight at Chamberlain.
Watford then staged a rally of their own and might have equalised on two occasions. First, after 55 minutes, Micah Hyde stubbed his shot wide, before Jones came to Saints' rescue again seven minutes later.
A good move down the Watford right saw Ardley deliver a deep cross. Chopra, on loan from Newcastle, won the header and his effort shaved the head of Paul Telfer before Jones tipped it over the bar.
The crucial second goal arrived when Ormerod chased a loose ball in the far left corner and delivered a dangerous low cross into the six-yard box. Beattie challenged for the vital touch along with Gayle and Robinson, and as all three crashed to the ground in a heap the ball went in off the Watford left-back.
Southampton were given a late scare when Ardley curled in a corner from the right and Gayle won a header which sailed into the far top corner, but they held their nerve and were able to celebrate a victory which sets up an all-Premiership FA Cup final which they can approach with some confidence.