Billy Sharp stuck out a toe to turn Adam Lallana's volleyed shot past Joe Murphy in the 16th minute, and moments later Jose Fonte's stooping header found the net to make it 2-0.
When Jos Hooiveld lashed in a third just before the hour mark and Lallana notched a fourth moments later, the party got under way.
Now the job to stay up - we a look at their promotion-winning squad and assesses where they will need to strengthen in the summer.GOALKEEPERS
Kelvin Davis has proved instrumental in Southampton's recent success and boasts top flight experience. The 35-year-old is at his peak and has been included in the PFA's team of the year in successive seasons. Saints, though, are in need of a proven back-up as Bartosz Bialkowski has become increasingly unreliable.
'We will score more goals than you' seems to have been Southampton's philosophy this season. That may have worked in the Championship, but they will need to strengthen in defence this summer.
Danny Fox at left-back is one player that could make the step up and has played in the Champions League for Celtic. Dan Harding has proved a decent understudy in the Championship but may struggle to step up, while fellow left-back Ryan Dickson is almost certain to depart.
On the opposite flank, Frazer Richardson and Danny Butterfield have shared game time this season. The pair's crosses have proved an invaluable tool going forward, but they may struggle defensively to cope with the likes of Gareth Bale, Nani and Co.
Saints have run with the partnership of Jos Hooiveld and Jose Fonte at the heart of defence. The former lacks pace but has the ability to make an impression in the top flight, but fellow centre-back Fonte may drop out of the starting line-up. Former non-league centre-half Aaron Martin provides decent back-up but lacks experience, while Danny Seaborne is still on the road to recovery after a nightclub attack left his career in danger. Experienced but injury-plagued Radhi Jaidi could well leave this summer.
Southampton's midfield is arguably their strongest department, although it will need a few tweaks.
One player sure to take the Premier League by storm is Adam Lallana, who was on the three-man shortlist for Championship player of the year. A graduate of the famousSouthampton academy, he has established himself as an integral player for the south coast club.
Morgan Schneiderlin is another that can make the step up, while Jack Cork and Richard Chaplow should also perform well. There are questions, though, over captain Dean Hammond's ability to cut it in the top flight.
Steve de Ridder has established himself as a fan favourite since joining last summer but, while his pace threatens down the flanks, he often lacks positional awareness. Jason Puncheon is another option and has recent Premier League experience with Blackpool and QPR.
Southampton boast one of the most prolific scorers in English football in Rickie Lambert. Having netted for fun in the third tier with Bristol Rovers and then Saints, he has gone onto prove himself in the Championship - scoring 25 goals and providing 11 assists this season.
Billy Sharp and Tadanari Lee will provide good options for Saints as will Guly do Prado, who can also provide cover in midfield. Improvements will be needed as the side lack pace with the likes of David Connolly and Lee Barnard potentially moving on.
Southampton boast an impressive core but the squad will need improving both in terms of strength and depth. The academy will undoubtedly provide a few talented players over the coming year or so, but Saints cannot afford to wait for another star and will need to splash the cash in the summer.