Match ends, Cardiff City 0, Southampton 3.
Southampton ended a six-game winless run with a comprehensive victory over troubled Cardiff City.
City's fans protested before kick-off against controversial owner Vincent Tan but that same fight and passion was not matched by the Cardiff players - who were easily beaten by the Saints.
Jay Rodriguez slid in at the back post to open the scoring, before his close-range volley doubled their lead.
Lambert made it 3-0 from close range inside 27 minutes to seal victory.
The result sees Southampton remain in ninth while Cardiff slide down to 16th in the Premier League table, a point off the bottom three, as pressure continues to mount on manager Malky Mackay - who was recently asked to quit or be sacked by Tan.
Mackay's departure looked inevitable before Cardiff chairman Mehmet Dalman released a statement on Sunday that indicated he would remain in charge for the "foreseeable future".
Dalman is trying to repair the fractured relationship between manager and owner but those efforts could be severely tested after an inept first-half performance from the Scot's side.
However, his afternoon could have been a lot different had Peter Whittingham not spurned an early chance for the Bluebirds.
The unmarked striker found space in the Saints box but side-footed Craig Noone's cross high and wide of Paulo Gazzaniga's goal.
He was soon made to pay for that miss with Rodriguez giving Saints the lead after sliding the ball home at David Marshall's back post after a wonderful cross by England colleague Adam Lallana.
Rodriguez soon doubled their lead, again finding himself unmarked at the back post as he volleyed home Lambert's cross to punish yet more slack defending from the hosts.
Lambert then got in on the act, firing home a half-volley from close range following a Rodriguez knock-down to further compound Cardiff's misery.
To their credit Mackay's side did not give up and Andrew Taylor's shot, which deflected off Jose Fonte, forced Gazzaniga into a sprawling save.
Cardiff introduced Andreas Cornelius at half time and he almost made an immediate impact, heading a corner wide from close range, while at the other end Jack Cork fired a fierce drive from range straight at Marshall.
Rodriguez went in search of his hat-trick and was denied by a wonderful headed clearance under his own post by Cardiff's Kevin Theophile-Catherine.
It was the last real action of a lacklustre second half, but Saints' early efforts ensured the outcome had long been decided.
See a photo gallery of all the action from Saturday's Premier League matches on the BBC Sport Facebook site.
Southampton manager Mauricio Pochettino:
"The victory today was fully deserved. We were amazing today, we were excellent.
"It was important to regain our confidence and not concede a goal. It had been nine games without a clean sheet so today was important for our confidence.
"We controlled the match but we were superior to them. We were precise and my players were very brave.
"The entire team put in an amazing performance today but of course one player will get the credit but the whole team deserves credit.
"There is a long time left until the World Cup so let us enjoy today and take it each game at a time.
"There are many games coming so it was important for our confidence especially after six games with no win. It was important to get that winning feeling back."
- 3TaylorSubstituted forJohnat 61'minutes
- 16NooneBooked at 22mins
- 17GunnarssonSubstituted forKimat 80'minutes
- 11OdemwingieSubstituted forCorneliusat 45'minutes
- 23ShawBooked at 25mins
- 4SchneiderlinBooked at 48mins
- 6José Fonte
- 9RodriguezSubstituted forRamírezat 86'minutes
- 7LambertSubstituted forGallagherat 90+3'minutes
- 20LallanaSubstituted forWard-Prowseat 80'minutes
- Andre Marriner
- Shots on Target
Second Half ends, Cardiff City 0, Southampton 3.
Substitution, Southampton. Sam Gallagher replaces Rickie Lambert.
Attempt missed. Steven Caulker (Cardiff City) header from the centre of the box misses to the right. Assisted by Peter Whittingham with a cross following a corner.
Corner, Cardiff City. Conceded by Calum Chambers.
Attempt missed. Kévin Théophile-Catherine (Cardiff City) right footed shot from outside the box is too high. Assisted by Craig Noone.
James Ward-Prowse (Southampton) wins a free kick in the defensive half.
Foul by Kim Bo-Kyung (Cardiff City).
Foul by Jose Fonte (Southampton).
Fraizer Campbell (Cardiff City) wins a free kick on the left wing.
Substitution, Southampton. Gastón Ramírez replaces Jay Rodriguez.
Attempt missed. Craig Noone (Cardiff City) left footed shot from outside the box misses to the left. Assisted by Fraizer Campbell.
Corner, Southampton. Conceded by Ben Turner.
Substitution, Cardiff City. Kim Bo-Kyung replaces Aron Gunnarsson.
Substitution, Southampton. James Ward-Prowse replaces Adam Lallana.
Adam Lallana (Southampton) wins a free kick in the attacking half.
Foul by Aron Gunnarsson (Cardiff City).
Foul by Jack Cork (Southampton).
Craig Noone (Cardiff City) wins a free kick in the defensive half.
Offside, Cardiff City. David Marshall tries a through ball, but Fraizer Campbell is caught offside.