In-form Danny Ings struck again as Southampton recorded successive Premier League victories for the first time since March by inflicting a damaging defeat on fellow strugglers Norwich.
Saints top scorer Ings scored for the fourth successive top-flight game, before a rare Ryan Bertrand goal put the home side in complete control against their relegation rivals.
Norwich improved after the break and halved the deficit through Teemu Pukki but the hosts clung on as Southampton boss Ralph Hasenhuttl celebrated a year in charge with a precious three points.
Saints began the game only three points better off than when the Austrian was appointed on 5 December last year following Saturday's much-needed victory over bottom club Watford.
Norwich, meanwhile, arrived on the south coast only a point and a place below their opponents and bidding to build on four points from their previous two fixtures.
Wednesday evening's clash was a meeting of the two worst defences in the division.
There was little to trouble either leaky backline during a dour opening 22 minutes before Saints went ahead with the game's first clear chance.
After being fouled on the left by Todd Cantwell, James Ward-Prowse delivered an inviting free-kick, allowing Ings to rise in front of Ben Godfrey at the near post and head home his 10th goal of the season in all competitions.
The breakthrough was the first time Saints had opened the scoring on home soil since the final game of last season, with Ings or Ward-Prowse responsible for their previous 11 league goals, dating back to 14 September.
The second of those two statistics was ended two minutes before the break as the hosts deservedly doubled their advantage.
Shane Long, recalled to make his 100th Saints start, flicked on Ward-Prowse's corner from the right and left-back Bertrand volleyed home his first goal since August 2018 from inside the six-yard box.
Norwich boss Daniel Farke had stuck with the starting XI which was unfortunate to only draw against Arsenal on Sunday.
But a dismal first-half display which passed without a meaningful attempt at goal forced him into a reshuffle at the break as midfield duo Marco Stiepermann and Alexander Tettey replaced Tom Trybull and Ibrahim Amadou.
Within a minute of the restart, Pukki had the Canaries' first attempt on target, stinging the palms of Saints goalkeeper Alex McCarthy from the edge of the box.
Southampton were then denied a 56th-minute penalty when referee Kevin Friend showed little interest in Godfrey's apparent push on Long.
Saints had looked in a healthy position to record a first home clean sheet of the campaign before Pukki pulled one back in the 65th minute to make a game of it.
Tettey's through ball split the hosts' defence and Finland striker Pukki raced clear to beat McCarthy with a rising left-footed finish and claim his eighth Premier League goal of the season.
The goal increased the anxiety levels in the stands but, despite some nervy moments in the closing stages, Saints hung on during four minutes of added time to boost their survival hopes.
Sam Byram wasted the Canaries' final opportunity by slicing off target, leaving Hasenhuttl to celebrate on the pitch with the relieved home fans.