Nathan Tella struck his first Southampton goal just two minutes after arriving off the bench as Saints chalked up back-to-back Premier League home wins for the first time since they were top in November against Fulham.
Ché Adams took his tally to nine for the season with the only goal of a first half Saints controlled, before Tella slotted home at the far post on the hour mark – a memorable moment for the 21-year-old, who has enjoyed a promising breakout season with the first-team.
The visitors then fought back when youngster Fabio Carvalho crashed home a shot via the underside of the crossbar 15 minutes from time, but Tella turned provider for fellow Academy graduate Theo Walcott, 11 years his senior, who helped secure back-to-back 3-1 victories.
Ralph Hasenhüttl made two changes in personnel and one in position following Tuesday’s comprehensive come-from-behind win against Crystal Palace.
Fraser Forster, who saved a penalty that night, was back on the bench as Hasenhüttl kept his promise of rotating his keepers for the run-in.
That meant a start for Alex McCarthy as well as Mohammed Salisu, who came in at left-back, prompting Jack Stephens to revert to his natural centre-back berth in the absence of the injured Jan Bednarek, nursing an ankle problem.
Fulham, playing their first match since their relegation was confirmed on Monday, made four alterations, including ineligible Saints loanee Mario Lemina, who was among those to drop out.
It was Saints who made the slicker start in driving rain at St Mary’s. Takumi Minamino drifted in from the right to find Nathan Redmond, but the angle was against him and his shot skewed wide of the near post.
Minamino was involved again when fed by Adams with a smart square pass, only for Tosin Adarabioyo to make a fine recovery challenge that took the sting out of the shot, allowing skipper Joachim Andersen to clear from under his own crossbar.
The Cottagers were on the back foot and Saints made them pay on 27 minutes. Awarded a free-kick to the right of the penalty area, James Ward-Prowse whipped in an almost undefendable delivery that Adams did well to steer into the net on the half-volley from close range.
Whilst Saints could be accused of having nothing to play for, to coin an end-of-season cliché, there could be no doubting the intensity of this display.
Ward-Prowse, one goal behind Adams on eight for the season – already a career high – eyed up the chance and forced Alphonse Areola into a decent save high to his right, though the keeper had stood his ground and ought not to be beaten on his side of the wall.
Meanwhile, Danny Ings, twice a scorer in midweek, was hunting for more goals to enhance his England chances with Gareth Southgate’s Euro 2020 squad announcement looming.
Constantly lurking on the shoulder of the last defender, he latched on to a clever reverse pass from Armstrong only to be forced wide by the onrushing Areola, prompting a cross rather than a shot, which invited Andersen to clear.
The second half would follow a similar pattern as Saints hunted more goals. Adams showed customary awareness to zip a first-time pass into the path of Redmond, whose shot threatened to squirm over the line but Areola got just enough on it with his legs to keep the hosts at bay.
Ings was withdrawn before the hour mark in a bid to conserve his energy, with two more games to come over the next eight days, and replacement Tella soon stole the show.
Tella shines from the bench
With virtually his first touch of the ball, the 21-year-old was in the right place to slot home at the far post to finish off a flowing team move in which Kyle Walker-Peters provided the assist with a teasing low cross along the six-yard line.
It was a moment to savour for Tella, who wheeled away in delight – a sight Saints fans will hope to witness in person many times in the future, with crowds due back at St Mary’s from next week.
At this point the game felt won, but Saints have been lacking clean sheets of late and McCarthy would have been determined to strengthen his claims to be long-term No. 1 with a welcome shutout.
For that he would need help from Stephens, who timed his tackle perfectly to dispossess Ivan Cavaleiro in the box with little margin for error, and later threw himself in the way of a shot from Ademola Lookman.
The visitors had found some confidence, and after substitute Joe Bryan whistled one wide from 20 yards, Carvalho found the net to halve the deficit 15 minutes from time, driving the ball in off the underside of the crossbar to leave McCarthy no chance.
Saints seal three points
But Saints were not finished, as Walcott followed in the footsteps of Tella by making an instant impact from the bench, starting and finishing an excellent team move as he dispatched Tella’s neat backheel with a first-time shot from the edge of the box.
It was Walcott's third goal since returning to the club that launched his career, and his first in a Saints shirt back at St Mary's in 15 years.