Sekou Mara’s first brace in English football fired Southampton to a 3-0 FA Cup replay victory over Watford and a fifth-round meeting with Liverpool.

Mara smashed two strikes into the near post to score his fourth and fifth goals of the season.

Che Adams added gloss to the victory to take Saints to a 24th game undefeated and set up potentially Jurgen Klopp’s last FA Cup tie before he leaves the Reds in the summer.

Both sides made seven changes a piece from their weekend exploits in the Championship and that showed in an opening 20 minutes devoid of quality.

Hornets defender Wesley Hoedt, against his former club, and winger Matheus Martins had off-target efforts at one end, and Saints teenager Tyler Dibling dragged wide at the other as the rain swirled around St Mary’s.

The deluged pitch meant Saints’ usually slick passing was impacted, although midfielder Flynn Downes forced a tricky moment for Daniel Bachmann after slipping in behind.

The game livened up when Southampton goalkeeper Joe Lumley was left rooted as Ismael Kone’s long-range drive deflected up and skidded onto the cross bar.

Lumley was equal to Kone a little later when the Ivorian midfielder diverted Martins’ cross towards goal.

And at the other end, Bachmann’s feet improbably denied Adams from five yards in the 28th minute before Mara fired an effort wide from a corner.

The hosts continued to dominate the ball without much cutting edge, although Joe Rothwell swung a shot wide and Bachmann smothered at Will Smallbone’s feet.

Adams and Mara switched positions in the second half and it proved the perfect alteration seven minutes after the restart.

Adams, now on the left, diverted the ball through to the central Mara and the Frenchman sent Bachmann the wrong way to finish into the near post.

Adams reverted to the middle after the goal and controlled over his shoulder and then volleyed over the bar as Saints pushed for a second.

And it came six minutes after the first as Mara emphatically finished a counter-attack by thumping into the near post again, this time from outside the box.

Bachmann walked straight off following the goal, having felt his head in the first half and pointed to his eye as he was replaced by Ben Hamer.

Samuel Edozie came off the bench and should have firmly put the game to bed when brilliantly threaded through by Rothwell but he stumbled and eventually scuffed a shot straight at Hamer.

Adams finally got the goal his persistence deserved when he calmly diverted Rothwell’s sumptuous free-kick from the left flank past Hamer.

Mara curled a late effort wide but could not add the match ball as a reward for his sparkling performance, while Edozie and Sam Amo-Ameyaw both struck the post.