Rickie Lambert scored a hat-trick to send Southampton back to the top of the Championship table with a comfortable victory at Watford.
The striker looped a header over home keeper Tomasz Kuszczak, who was making his debut following a loan move from Manchester United, to put Saints ahead.
Lambert fired in from the edge of the box before completing his hat-trick after the break from the penalty spot.
John Eustace headed wide to waste Watford's best chance of a consolation.
The home side created few other chances against a Saints side that extended their unbeaten run to six games.
The visitors were quickly into the ascendancy, Lambert taking advantage of a hesitant Kuszczak to nod in the opener from Jose Fonte's cross in the 13th minute.
Eight minutes later the Championship's leading scorer drilled in his 18th goal of the season from Adam Lallana's pull-back.
Saints should have extended their lead further shortly after the break but Tadanari Lee scooped a chance over the crossbar.
Lee had a second chance to score 20 minutes from time but Kuszczak denied him with a fine save, however the Japanese striker earned a penalty when he was pushed in the aftermath by Carl Dickinson and Lambert rifled his 19th of the season into the top corner from the spot.
Southampton boss Nigel Adkins: "Rickie Lambert is a talented, talented football player but we have won this season when Rickie's been out.
"Rickie was sent off at Brighton for a terrible refereeing decision and we lost him for three games.
"We won two of them so it's not as if we can't win without Rickie, but he is an exceptionally good football player who not only scores goals but creates goals."
Watford boss Sean Dyche: "I'm disappointed to have not performed really.
"You can't guarantee results any week and certainly not when a top-of-the-table side come to town but we pride ourselves on performance levels and we feel that today we came away from performance levels and obviously against anyone that can undo you but certainly against the market leaders.
"We wanted to make changes to freshen it up and give a bit of zip to it and we just came away from it today."
- 35 Kuszczak
- 03 Dickinson
- 06 Mariappa
- 12 Doyley
- 33 Nosworthy
- 04 Eustace
- 07 Yeates (Buaben - 84' )
- 18 Kacaniklic (Iwelumo - 78' )
- 32 Hogg
- 09 Deeney
- 20 Trotta (Garner - 59' )
- 01 Loach
- 17 Bennett
- 19 Buaben
- 10 Iwelumo
- 25 Garner
- 01 Davis
- 06 Fonte
- 12 Butterfield
- 13 Fox
- 26 Hooiveld Booked
- 04 Schneiderlin
- 08 Cork
- 18 Chaplow (Hammond - 77' )
- 20 Lallana (Puncheon - 29' Booked )
- 07 Lambert (Connolly - 84' )
- 19 Lee
- 16 Martin
- 14 Hammond
- 42 Puncheon
- 11 Sharp
- 22 Connolly
Live Text Commentary
Full Time The referee brings the game to a close.90:00 +3:28
Shot by Jack Cork from deep inside the penalty area misses to the right of the goal.90:00 +2:44
Lloyd Doyley delivers the ball, save by Kelvin Davis.90:00 +1:43
Foul by John Eustace on Tadanari Lee, free kick awarded. Danny Butterfield takes the free kick.89:43
The assistant referee signals for offside against Chris Iwelumo. Indirect free kick taken by Kelvin Davis.88:48
A cross is delivered by Troy Deeney, Joe Garner takes a shot. Save by Kelvin Davis. The ball is sent over by Troy Deeney.83:51 Substitution
Substitution David Connolly replaces Richard Lambert.83:35 Substitution
Substitution Mark Yeates leaves the field to be replaced by Prince Buaben.83:13
The ball is crossed by Carl Dickinson.82:36
Free kick awarded for a foul by Jose Fonte on Chris Iwelumo. Carl Dickinson takes the direct free kick.79:08
Centre by Nyron Nosworthy, Header by Joe Garner from deep inside the penalty area misses to the left of the goal.77:59 Substitution
Substitution Chris Iwelumo on for Alex Kacaniklic.76:23
Kelvin Davis takes the free kick.76:23 Substitution
Substitution (Southampton) makes a substitution, with Dean Hammond coming on for Richard Chaplow.76:23
Foul by Troy Deeney on Jose Fonte, free kick awarded.74:34
Mark Yeates crosses the ball.73:29
Corner taken by Mark Yeates from the right by-line played to the near post.73:15
A cross is delivered by Troy Deeney, Jos Hooiveld manages to make a clearance.71:57
Tadanari Lee provided the assist for the goal.71:57 Goal scored
Goal! - Richard Lambert - Watford 0 - 3 Southamp'n Richard Lambert scores a power penalty. Watford 0-3 Southampton.
Foul by Carl Dickinson on Tadanari Lee, Penalty awarded.70:57
Tadanari Lee takes a shot. Save made by Tomasz Kuszczak.69:39
Free kick awarded for a foul by Carl Dickinson on Tadanari Lee. Free kick taken by Kelvin Davis.69:29
The ball is swung over by Mark Yeates, Danny Butterfield manages to make a clearance.69:02
Corner taken by Mark Yeates from the left by-line to the near post, Daniel Fox manages to make a clearance.67:54
The ball is crossed by Jason Puncheon.67:31
The ball is crossed by Danny Butterfield, Tomasz Kuszczak makes a save.66:26
Alex Kacaniklic delivers the ball, Shot from deep inside the area by Troy Deeney clears the bar.66:01
Free kick awarded for an unfair challenge on Joe Garner by Jose Fonte. Free kick taken by Lloyd Doyley.65:34 Booking
Booking Jason Puncheon is cautioned.62:00
Free kick awarded for a foul by Mark Yeates on Danny Butterfield. Kelvin Davis restarts play with the free kick.59:32
Foul by Richard Lambert on Lloyd Doyley, free kick awarded. Tomasz Kuszczak takes the direct free kick.58:56 Substitution
Substitution Joe Garner is brought on as a substitute for Marcello Trotta.57:27
The ball is crossed by Jonathan Hogg, save by Kelvin Davis.56:53
Inswinging corner taken from the left by-line by Mark Yeates.56:46
A cross is delivered by John Eustace, clearance made by Danny Butterfield.55:28
Marcello Trotta gives away a free kick for an unfair challenge on Jose Fonte. Direct free kick taken by Kelvin Davis.54:41
Long distance shot from Tadanari Lee misses to the left of the net.54:18
Header from close range by John Eustace misses to the right of the goal.54:01
Mark Yeates produces a cross.53:41
Lloyd Doyley takes the free kick.53:41 Booking
Booking The referee shows Jos Hooiveld a yellow card for unsporting behaviour.53:19
Jos Hooiveld concedes a free kick for a foul on John Eustace.52:02
Carl Dickinson gives away a free kick for an unfair challenge on Richard Chaplow. Kelvin Davis takes the free kick.51:40
The ball is crossed by Richard Chaplow, Tomasz Kuszczak makes a save.50:40
Morgan Schneiderlin produces a right-footed shot from long range which goes wide right of the goal.48:37
Troy Deeney is caught offside. Free kick taken by Kelvin Davis.47:34
A cross is delivered by Richard Chaplow, Close range strike by Tadanari Lee goes over the bar.46:35
Jason Puncheon produces a cross.45:01
The referee gets the second half started.45:00 +3:12 Half time
Half Time The referee calls an end to the first half.45:00 +3:00
Lloyd Doyley sends in a cross, save by Kelvin Davis.45:00 +2:51
Centre by Carl Dickinson, clearance by Daniel Fox.45:00 +0:45
The ball is swung over by Daniel Fox, clearance by Adrian Mariappa.42:23
The ball is sent over by Jason Puncheon, save by Tomasz Kuszczak.39:57
John Eustace gives away a free kick for an unfair challenge on Morgan Schneiderlin. Free kick taken by Kelvin Davis.38:47
John Eustace is ruled offside. Kelvin Davis restarts play with the free kick.38:08
Jos Hooiveld challenges Troy Deeney unfairly and gives away a free kick. The free kick is swung in left-footed by Alex Kacaniklic.36:31
Troy Deeney sends in a cross, clearance by Jose Fonte.35:59
The ball is swung over by Richard Lambert, clearance made by Adrian Mariappa.34:34
The ball is swung over by Lloyd Doyley, save made by Kelvin Davis.34:20
The ball is swung over by Alex Kacaniklic, clearance by Daniel Fox.29:21
Centre by Lloyd Doyley, Richard Chaplow makes a clearance.28:54 Substitution
Substitution Jason Puncheon replaces Adam Lallana.27:25
Tadanari Lee concedes a free kick for a foul on John Eustace. Adrian Mariappa restarts play with the free kick.26:11
The referee gives a free kick against Richard Chaplow for handball. Mark Yeates takes the direct free kick.25:15
Mark Yeates produces a cross, Alex Kacaniklic produces a mishit left-footed shot from 12 yards. Blocked by Danny Butterfield. Mark Yeates takes a inswinging corner from the left by-line to the near post, clearance made by Jose Fonte.23:03
The referee blows for offside. Kelvin Davis restarts play with the free kick.20:59
Assist on the goal came from Adam Lallana.20:59 Goal scored
Goal! - Richard Lambert - Watford 0 - 2 Southamp'n Richard Lambert finds the back of the net with a goal from just outside the penalty box to the bottom left corner of the goal. Watford 0-2 Southampton.19:16
Alex Kacaniklic concedes a free kick for a foul on Richard Chaplow. The free kick is delivered right-footed by Daniel Fox from right channel, clearance made by Adrian Mariappa.16:30
Jonathan Hogg takes a shot from deep inside the box clearing the bar.15:54
Inswinging corner taken from the right by-line by Alex Kacaniklic, clearance by Daniel Fox.15:33
Richard Lambert takes a shot. Save made by Tomasz Kuszczak.15:24
A cross is delivered by Daniel Fox, clearance made by Adrian Mariappa.12:04
The assist for the goal came from Jose Fonte.12:04 Goal scored
Goal! - Richard Lambert - Watford 0 - 1 Southamp'n A goal is scored by Richard Lambert from inside the area low into the middle of the goal. Watford 0-1 Southampton.9:53
The referee penalises Tadanari Lee for handball. Free kick taken by Nyron Nosworthy.5:25
Marcello Trotta crosses the ball.2:34
Adam Lallana is penalised for a handball. Free kick taken by John Eustace.0:12
Adrian Mariappa gives away a free kick for an unfair challenge on Tadanari Lee. Free kick crossed left-footed by Daniel Fox, clearance by Troy Deeney.0:00
The ref blows the whistle to begin the match.
Live data and text provided by our data suppliers