Three second-half Southampton strikes sent Watford crashing out of the Emirates FA Cup in tonight’s fourth-round replay at a rain-soaked St Mary’s.

Having played out a 1-1 draw in the initial tie at Vicarage Road, there was once again little to separate the sides during the opening 45 minutes – Ismaël Koné striking the bar at one end and Che Adams drawing a good save from Daniel Bachmann at the other.

Two quickfire Sekou Mara goals settled the tie after the interval, with Adams adding a third later in the half to secure a 24th match without defeat for the Saints and a trip to Liverpool in the fifth round.

Valérien Ismaël opted for seven changes to the starting XI that faced Cardiff City on Saturday with Ken Sema a notable inclusion, the Sweden international making his first start since suffering a muscular injury on Boxing Day.

Other than a couple of early half-chances for the Hornets – with Wesley Hoedt heading wide and Matheus Martins dragging a tame shot off-target – the opening 20 minutes passed with little goalmouth action as the teams tried to adjust to a greasy playing surface in blustery conditions.

The game came to life with a flurry of chances midway through the first half, with returning Watford goalkeeper Bachmann keeping out a Flynn Downes effort. Then after a swift counter-attack – led by Giorgi Chakvetadze – Koné saw a deflected strike from distance hit the top of the bar.

From Chakvetadze’s resulting corner, Francisco Sierralta saw a back-post header fly just the wrong side of Saints keeper Joe Lumley’s post.

Southampton seemed destined to take the lead through Adams but the striker was denied by a superb Bachmann save from point-blank range, with Hoedt then diving in to lash the loose ball behind for a corner.

A trademark Hoedt diagonal switch found Martins on the right-hand side and when the Brazilian delivered his cross, Koné’s first-time shot was caught comfortably by Lumley.

A loose Martins pass then set Southampton away in the latter stages of the half and when Tyler Dibling slipped in Will Smallbone, Bachmann was off his line quickly to smother the angled shot.

There were no changes to either side during the interval, and no respite from the wet and windy south-coast weather.

The Hornets appealed for a penalty three minutes after the break when Chakvetadze went down under a challenge in the box, but referee Darren Bond ruled the fall to be simulation and the Georgian was duly booked.

Southampton opened the scoring with 52 minutes played when Mara was slipped in on goal by Adams and the French forward fired low into the bottom corner to make it 1-0 to the hosts.

Ismaël responded immediately with a triple change – Ryan Andrews, Jamal Lewis and Yáser Asprilla replacing James Morris, Chakvetadze and Sema.

Visibly energised by the goal, Southampton drove forward with another sweeping move and Mara was on the end of it once more, this time drilling a superb effort into the back of the net from outside the box for his second goal in the space of six minutes.

While the teams were preparing for the restart, Ben Hamer came on in goal for the seemingly concussed Bachmann. Vakoun Bayo then replaced Mileta Rajović in attack.

Two became three soon after, the unmarked Adams meeting Joe Rothwell’s free-kick from the left flank with a side-footed volley that was dispatched neatly beyond Hamer as the game entered its final 15 minutes.

Seeking a hat-trick, Mara’s eyes lit up when faced with a shooting opportunity on the edge of the Watford box but his curling shot was wide of the target. Then substitute Sam Edozie was sent clean through on goal and saw his shot rebound off the foot of the post.

Koné was withdrawn for Tom Ince in the closing stages, and there was just enough time for Sam Amo-Ameyaw to hit the woodwork in the final moments of stoppage time.

Leicester City await the Hornets on Saturday (February 10, 3pm KO), with focus for the remainder of the season set firmly on matters in the Sky Bet Championship.