Manchester United stretched their winless run to three games in the league after they lost for the first time since November 2.
It also meant the Red Devils have won just one of their last five league games.
The Saints leapfrogged United to third in the table after they prevented United having a shot on target. The Saints were the better team despite United having the majority of the possession.
Time for a change of Philosophy
Since the day Louis Van Gaal walked through the door at Old Trafford he has failed to stop using the word "philosophy."
The most famous part of his philosophy is the much questioned 3-5-2 formation.
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As we know, 3-5-2 is a system the Dutchman is accustomed to as seen at this years World Cup. In fairness, it was very successful.
This though this is a totally different kettle of fish. The difference is the Dutch side had all their players playing in their favoured position. United don't and that was clearly evident at Old Trafford on Sunday.
Firstly we saw utility man Daley Blind deployed alongside Phil Jones and Chris Smalling as part of the back three. Also Angel Di Maria was playing up front and Wayne Rooney upfront.
These decision were not only strange but also wrong. Rooney has been a striker all his career while Di Maria's best performances in a red shirt have come when he's payed in the middle of the park where he can pick the ball up and use his explosiveness to run at defences.
United's better performances have come when the team plays four at the back and a diamond in midfield. It has a position for everybody at the club.
For example, Rooney and Juan Mata play behind the two strikers. Di Maria, Ander Herrera and Adnan Januzaj are the two in the middle of the diamond, then Daley Blind or Michael Carrick is the holding player. It works better with what Van Gaal has got. United need a change to get back on track. Is a change in formation the way?
Selection headaches, now migraines for United fans
One thing United do have is options. Especially now that they only have one player injured. So it was a shock to see that Radamel Falcao was not included. Van Gaal said it was because he has played the last five games. It was still a strange decision as Falcao's form is improving while Robin Van Persie has had a little dip.
Van Persie is now 31. So maybe squad rotation will do him good to keep him fresh. Plus he is a cracking player to bring off the bench.
With United lacking invention a lot in recent times, it makes one wonder as to why Ander Herrera is often sitting on the bench. Whenever he plays United's tempo quickens, the ball is moving quicker and more importantly it's in a forward direction. He also has genuine quality as shown with his wonder strike at Yeovil. All he is lacking is consistency. But how can he get any sort of rhythm going if he's in and out of the side?
Another story in itself is United's defence. I could write a one-million word piece on United's defence but i'm not going to bore you.
United were without Marcos Rojo on sunday despite him being declared fit. He has arguably been the shining light out of all of United's defenders. United have lost just two of the 11 games he has played. This should surely justify him a place in the side?
The likes of Jonny Evans and Tyler Blackett both made the bench instead of Rojo. Evans, has in fairness, had a few nightmare performances. Most notably against Stoke and MK Dons. Tyler Blackett hasn't faired better despite early season promise.
United have had defenders that have struck fear into strikers up and down the country over the years. Now the only people they are striking fear into is United fans. When's the next mistake coming? who's going to lose their man?
What next? Will United sign anyone?
You don't need to be Einstein to work out what Manchester United need. It's a commanding centre half. A leader. Before Sunday's game It looked unlikely that there was going to be anymore additions at Old Trafford. Though that result could act as a wake up call. Especially after the reaction of United fans. Some took their complaints way to far, some crazy enough to call for Van Gaal to be sacked, which is utter nonsense.
The question is are the likes of Mats Hummels, Raphael Varane and Diego Godin all available in January? the answer is probably no. Those are the players Manchester United need to be chasing.
In the mean time do they look for a quick fix? possibly. Ron Vlaar seems to fit the bill. Van Gaal was rumoured to be interested in the summer. He knows Vlaar well through his time at Holland. He will certainly add experience to help the likes of Jones and Smalling.
In the mean time the likes of Jonny Evans and Tyler Blackett should be shown the door if United to make a signing. They are simply not good enough for United. As honest and as dedicated they are, they just dont fit the bill.
There has been talk of Kevin Strootman signing as well. Though surely Morgan Schneiderlin is the one they should be chasing. He is proven in the Premier League. Apart from Nemanja Matic, He is the best player in his position. It's surely a no brainer?