The Hornets want to get back to Herts ASAP.
Southampton's Dusan Tadic attempts to score a spectacular second but blazes over from 12 yards.
Moments later Jose Holebas gets a splendid toe on the ball to deny Shane Long a second from eight yards.
Saints keeper Fraser Forster makes his first save of the match - in the 85th minute - diving steadily to his left to hold on to Craig Cathcart's low shot.
Saints striker Graziano Pelle is on after missing the last four matches with an injury. He's gets an expected little ovation from the home fans.
Saints are rampant. Steven Davis cruises down the right and plays a lovely low angled teasing delivery across goal, but Shane Long, at the far post, fails to get any connection under pressure.
With virtually his first touch of the ball, Dusan Tadic makes it 2-0. A long ball is played up to Steven Davis, whose first time headed flick finds Tadic.
The midfielder shifts the ball past Sebastian Prodl and Ikechi Anya and fires in from eight yards despite keeper Heurelho Gomes getting a hand to the shot.Copyright: Getty Images
Southampton go close again. Goalscorer Shane Long pulls the ball back for Sadio Mane, whose low drive drifts narrowly past the keeper's left-hand post.
The Senegal attacking midfielder is replaced with Dusan Tadic.
The Saints go close again. A free-kick is played into the area. Virgil van Dijk heads across the goal but Shane Long fails to connect and Sadio Mane finds the side-netting.
Well... that was close. I don't think he was offside.
A long ball is played from the back. Steven Davis runs on to it and fires an excellent shot past Heurelho Gomes, but it's deemed offside.
Moments later, the keeper pushes Oriol Romeu's 20-yard shot away.
Busy few moments at that end of the pitch.
It's smashing it down at St Mary's. Well done to all who turned up.
Scotland winger Ikechi Anya comes on for Almen Abdi.
Saints fans need to be reminded that Watford striker Odion Ighalo - who has seven goals in his last seven games - goes on until stoppage time.
Just a reminder.
It's Sadio Mane again. The livewire attacking midfielder - he's a striker really - teases his way to the edge of the area and tries to find Shane Long with a cheeky backheel, but Sebastian Prodl spots the danger.
Just like at the start of the first half, it's been quiet opening.
Odion Ighalo and Troy Deeney have barely seen the ball at St Mary's tonight.
Nothing comes from the corner. As you were.
He's back up. Good to see. Watford have a corner.
Sadio Mane goes in for a challenge with Heurelho Gomes. There's a clash of heads and the Watford keeper is down.
He's writhing around - understandably - and is getting treatment on the pitch.
The Saints get us back under way.
Robin Harris: Are Watford the only team playing 4-4-2 tonight in the Prem? Seems 4-2-3-1 is very popular tonight! #bbcfootball