SAINTS rescued their record-breaking unbeaten run for a 22nd match thanks to a late Stuart Armstrong equaliser in a 1-1 draw at Watford. 

The Scottish international kept Saints in the FA Cup as an early opener from Matheus Martins looked set to knock them out at the fourth round.

The Brazilian took advantage of poor wall organisation and shot-stopping from backup goalkeeper Joe Lumley in the sixth minute. 

Saints will now host the Hornets midweek in the week commencing Monday, February 5, as the home side held on through a flurry of late chances. 

The winners of the clash will book a midweek visit to Premier League challengers Liverpool in the fifth round at the end of February.

Manager Russell Martin made nine changes to his starting team from last weekend's win over Swansea - the same he made versus Walsall.

It affected Southampton's rhythm and their only sustained spells of pressure came in the closing stages after several substitutions had been made. 

There was a first start for academy starlet Tyler Dibling, just 17 years old, and a full Saints debut for January signing Joe Rothwell. 

Watford themselves made six changes but a handful of the players that featured in December's 1-1 Championship draw retained their places.

The hosts started much the quicker side, with Martins hitting the opener from a direct free-kick just five minutes in. 

Mason Holgate committed a yellow card offence wide of the box and goalkeeper Joe Lumley was punished for a one-man wall as Martins' strike nestled inside the post. 

Holgate's combination with Dibling on the right was just one of many offering very little and it was a drab affair at Vicarage Road for half an hour. 

Watford should have then doubled their lead as Lumley committed to sliding for a ball he could not reach.

Vakoun Bayo beat the goalkeeper to it wide of his box but the cross back in, which would have serviced an open goal, was over all of the Hornets attackers.

Taylor Harwood-Bellis was required to make an excellent last-ditch tackle on Bayo in the next phase of play before Saints crafted their first big chance of the day.

Charly Alcaraz slipped Dibling in behind and the youngster should have pressed on for a shot but, perhaps lacking confidence, unsuccessfully tried to play back across to a teammate.

The Saints fans - who packed the full away end - were given a lift as they showered Watford guest and legend, and former Portsmouth boss, Kenny Jackett with half-time boos. 

Martin opted against making any changes at the break, though, and Alcaraz wasted a free-kick in a dangerous area with a shot that was without power and well over at the same time. 

After an hour, the boss had seen enough. Martin introduced substitutes S Armstrong, Adam Armstrong, Will Smallbone and Ryan Fraser at the same time. 

They could not provide a spark and Sam Amo-Ameyaw was Southampton's fifth and final change with more than 10 minutes of regulation time left.

Holgate tested the wrists of Watford goalkeeper Daniel Bachmann with a vicious strike from range as Saints had a flurry of half-chances.

A Armstrong had one goalbound shot blocked after Holgate's clever dink into the box but it was the number nine's namesake with the decisive touch.

Mara had a shot well saved by Bachmann and S Armstrong's curled effort from the edge of the area wrongfooted the keeper to level proceedings.

Saints pushed for a winner, inspired by the fearlessness of young Amo-Ameyaw, but could not find a winner - they settled for an extension of the unbeaten run. 

Watford: Bachmann; Sierralta, Hoedt, Lewis (Morris, 62), Kone (Ince, 75), Pollock, Chakvetadze (Porteous, 86), Asprilla (Sema, 62), Bayo, Martins (Dennis, 75), Andrews.

Unused subs: Roberts, Livermore, Rajovic, Grieves. 

Booked: Chakvetadze. 

Saints: Lumley; Holgate, Stephens, Harwood-Bellis, Meghoma (Amo-Ameyaw, 79); Charles (Smallbone, 63), Rothwell (S Armstrong, 63), Alcaraz; Dibling (A Armstrong, 63), Mara, Adams (Fraser, 63). 

Unused subs: McCarthy, Walker-Peters, Manning, Bednarek.

Booked: Holgate, Alcaraz.

Referee: Michael Salisbury.