The Saints' remarkable unbeaten run continued at Rotherham United on the weekend, whilst the Hornets suffered a shock defeat against Cardiff City in Hertfordshire.
Match preview
Southampton extended their unbeaten run across all competitions to an outstanding 23 matches on Saturday afternoon, when the Saints made the long trip to Yorkshire to face relegation-threatened Rotherham, with the hosts ultimately unable to handle the power of the promotion chasers.
Centre-back Jan Bednarek got the visitors off to a perfect start in the fourth minute by netting the contest's opening goal, with Adam Armstrong netting his 15th goal of the Championship campaign before the half-time break, meaning the 26-year-old has now provided 26 goal contributions in 29 league games.
Russell Martin's men currently sit second in the second-tier standings after avoiding defeat in the league since their trip to Michael Carrick's Middlesbrough on September 23, with the South Coast club one point ahead of third-placed Ipswich Town but 11 points behind runaway leaders Leicester City.
Having netted 15 goals and set up 11 more for teammates, former Blackburn Rovers attacker Armstrong is in the race for the Championship's Golden Boot and playmaker award simultaneously, although the efforts of Che Adams cannot be underestimated, with the ex-Birmingham City striker scoring eight times.
Following Matheus Martins's opener for Watford in the original tie on January 28, it looked as if Southampton's unbeaten streak was coming to a disappointing end of Vicarage Road, however Stuart Armstrong's deceiving effort was enough to book his side's spot in the fifth-round draw.
Since the draw against Southampton, Watford have endured a tricky 10 days in the Championship, being forced to settle for a share of the spoils at strugglers Sheffield Wednesday before losing narrowly to Erol Bulut's Cardiff at Vicarage Road on Saturday afternoon.
A fine strike from former Blackpool winger Josh Bowler was enough to hand the Bluebirds maximum points in Hertfordshire, and despite dominating the possession and chance-creation statistics, the Hornets were unable to breach the net of 30-year-old goalkeeper Jan Alnwick.
Aiming to bounce back to the Premier League at the second attempt following relegation in May 2022, Valerien Ismael's men are currently 11th in the Championship table, four points behind sixth-placed Hull City, who recruited exciting talents such as Anass Zaroury and Fabio Carvalho in the January transfer window.
All of the last three meetings between Watford and Southampton have ended in stalemates, and the Hornets have failed to beat the Saints during their last 10 meetings at Vicarage Road, meaning Ismael's side will have to break an unwanted streak to book their place at Anfield in the fifth round.
Like the vast majority of teams within the English system, Watford have never managed to lift the FA Cup, although they did come relatively close in the 2018-19 term, reaching the final at Wembley Stadium before being hit for six by Pep Guardiola's Manchester City.
Southampton FA Cup form:
W
D
Southampton form (all competitions):
D
W
W
W
D
W
Watford FA Cup form:
W
D
Watford form (all competitions):
W
W
D
D
D
L
Team News
Southampton remain without the services of former Rangers midfielder Joe Aribo, who remains away with Nigeria on Africa Cup of Nations duty.
Ross Stewart is still sidelined due to a muscle injury and has not been able to make his full Saints debut just yet, featuring for just 17 minutes since arriving in the summer.
Kamaldeen Sulemana was a regular starter for Martin's side before sustaining a hamstring strain in November - the 21-year-old is expected back in the middle of February.
Watford are unable to call on the talents of midfielder Edo Kayembe, who picked up a calf injury last month and has not featured since the six-goal thriller at Plymouth Argyle.
Mileta Rajovic and Emmanuel Dennis started on the bench for the defeat against Cardiff, however it is likely that both are in from the off at St Mary's.
Southampton possible starting lineup:
Bazunu; Walker-Peters, Stephens, Harwood-Bellis, Manning; Downes, Rothwell, Charles; Brooks, Mara, Fraser
Watford possible starting lineup:
Hamer; Andrews, Pollock, Hoedt, Lewis; Livermore, Kone, Chakvetadze, Asprilla; Dennis, Rajovic
We say: Southampton 3-1 Watford
Southampton have home advantage in this winner-takes-all clash and they should be confident of extending their unbeaten run to 24 matches on Tuesday night.