Shane Long opened the scoring in the opening five minutes as he easily breezed through the Toon defence from 25 yards out. The forward took it past both Vurnon Anita and Steven Taylor, both of whom made very light challenges, before Long fired past Newcastle stopper Karl Darlow.
The second came just seven minutes before the break as Graziano Pelle scored his tenth goal of the Premier League season. This goal was all down to Newcastle's poor defending as right-back Daryl Janmaat fell 40 yards from goal which took Dusan Tadic through onto goal, before slotting it to Long whose poor touch found Pelle unmarked in the box to slot in and give the Saints the 2-0 lead before the break.
This result sees Saints remain in seventh place but, they closed the gap on 6th placed West Ham to just two points following the Hammers' thrilling 3-3 draw with Arsenal at the Boleyn ground this lunchtime.
Saints strike early
It was the Saints who were the dominant in the opening exchanges, controlling possession and winning a host of corners and piling the pressure onto this disappointing Newcastle side. It was no real shock that they took the lead after just four minutes as Long caused havoc to the Newcastle defenders throughout the match.
The Saints continued to be the impressive side through the first half and completely controlled the half as Jordy Clasie and Victor Wanyama completely won the battle in the middle of the midfield which allowed Pelle to net his 13th goal of the season just before the break after a further defensive mistake by Newcastle courtesy of a slip from Janmaat.
Whilst, Newcastle were largely disappointing the Saints continued to do their jobs well and kept their foots on the pedals which was certainly needed as a drop in the levels of complacency would have only been a negative thing for the Saints. Saints' fabulous run against Newcastle at St Mary's continued as they collected their fourth consecutive win against them, scoring 13 goals in the process with just one goal conceded.
Little canged in the second half
Saints, like in the first half, completely outplayed Newcastle and they collected their third goal through Wanyama. The goal came from a short corner from Clasie and it was played to Sadio Mane, who was easily able to get to the by-line and he sent it in to Pelle, who saw his shot blocked and the rebound was followed up by Wanyama, who smashed his effort in to the top right corner to kill the game. The goal was Wanyama's first since November 2014 when he scored a 40 yard strike away to Hull City at the KC Stadium.
The home side allowed Newcastle a route back into the game in the 65th minute through a fabulous strike from January signing Andros Townsend. Townsend scored the goal to give his side a slight lift with 25 minutes to go as the former Tottenham Hotspur man cut inside from the right before sending a thunderbolt past the helpless Fraser Forster.
Following the goal, Southampton introduced midfielder James Ward Prowse on in the place of Long, who caused trouble to throughout the hour which he played. The striker did take a slight knock in the first half so the Saints will hope that it's nothing more than a precaution from boss Ronald Koeman.
One sour note for Southampton
Although the Saints were superb throughout there was one thing which will be a worry for the them following the match. Charlie Austin picked up an injury whilst warming up prior to the game, which was thought to be a recurrence of his hamstring injury which he only returned back from in the loss to Leicester City last Sunday.
Austin is known for picking up regular injuries and this will be another frustration for the 26-year-old. who is yet to really find his feet after making the move to St Mary's in January from Championship club QPR. The forward didn't come out to warm-up with the rest of the substitutes which shows just how much of a worry this may prove to be for the Saints, who face a trip to Everton next weekend in what looks like another very challenging match.
On the other hand there was a return to action for Jay Rodriguez who returned to first team action for the first time since facing Leicester City in October when he replaced Tadic with seven minutes remaining which is a massive boost for everyone at the club.
Vital win for club
Following West Ham dropping points earlier in the day it was a great win for the Saints to install pressure onto the Hammers, who face a FA Cup tie against Manchester United this mid-week.
Chelsea also dropped points this afternoon as they slipped to a shock loss to Swansea City to help Saints case further as they pursuit European football once more after having a small taste of it last season before losing in the final play-off round.