There is not a lot of pleasure to be taken from ‘I told you so’ in football but there probably were quite a few thousand Saints fans thinking exactly that following the fantastic victory over Sunderland.

If there have been two consistent themes in the vast majority of conversations since the beginning of the season it has been frustration over the lack of a clinical striker – a feeling heightened by Charlie Austin’s long injury lay-off - and Claude Puel’s change in formation, and, therefore, style of play.

Saints moved for a forward in January, splashed out more than £14m, and have instantly reaped the benefits with Manolo Gabbiadini looking every inch the player that so many supporters have been calling for.

Puel has stuck fairly rigidly to his plans, his formation and style, and it seemed he would resist calls for change no matter how things were going.

But, having had the rare treat of a full week to work with his side on the training ground, he switched to the much missed 4-2-3-1 formation for the game at the Stadium of Light.

Let us just remember this was the formation used for the vast majority of the three previous seasons as Saints finished eighth, seventh and sixth. It is a formation the players are used to and have been successful with.

While Puel has come in for some unfair stick, it has felt perfectly reasonable to criticise the decision to change a winning formula, especially when it has had such mixed results.

So it was a very warm welcome back to the 4-2-3-1, and what a difference it made.

The players looked so comfortable playing it. They really did thrive.

It produced a team that looked balanced, defensively solid and able to find different routes towards goal.

When you then put Gabbiadini’s clinical finishing into the mix, and his link-up with Dusan Tadic, it was a winning formula.

At this stage we cannot be sure whether we will see it continue – hopefully so - or if this was a special plan for Sunderland, but Puel deserves credit for getting this correct.

We should also reflect that it is probably no coincidence this came after that full week to work with his squad.

For all the ups and downs, it really does feel like the time to judge Puel will be after the next few months.

He really needs the chance to show what he can produce when he doesn’t have the ridiculous fixture pile-up we saw in the first half of the season.

If what we witnessed at Sunderland was anything to go by it can be really positive.

The win not only eradicated any sense of unease that was starting to take hold after the bottom three edged a little closer to Saints in recent weeks but, crucially, provided some much needed confidence and momentum ahead of the EFL Cup final.

The last thing Saints needed was two weeks without a game to stew on another poor result or poor performance.

Instead what they have is two weeks of feeling great about themselves, confident and upbeat, with a chance to recover and properly prepare while Manchester United play another three games in the meantime.

The scoreline at the Stadium of Light accurately reflected the game.

After seeing off some early Sunderland enthusiasm, Saints turned the screw in empathic fashion, while the Black Cats first mentally cracked and later totally capitulated in embarrassing fashion.

The new formation saw Oriol Romeu and Steven Davis paired together and providing a great base to build form.

The full backs were able to attack, there was width, and Tadic dropping into pockets of space. Sunderland just didn’t know how to handle Saints’ quality, which was truly unleashed by the set-up.

Saints’ first goal on the half hour mark was a mixture of great play and a slice of luck.

Ryan Bertrand, again superb at left back, put in a cross which found the near post run of Gabbiadini.

Lamine Kone tried to head clear just ahead of him but didn’t make contact and the ball cannoned off of Gabbiadini’s body, most likely his arm, and gave Vito Mannone little chance of keeping it out.

Saints doubled their lead before half time in more convincing fashion as Tadic and Gabbiadini linked up.

Kone made a grave error in standing off of Gabbiadini in the area and paid the price as he saw the Italian quickly turn and then finish past Mannone.

Sunderland made attacking changes as the game went on but it only served to make them worse.

They never seriously tested Saints who were so comfortably on top the only question seemed to be how many they might run in.

The biggest surprise was that it took them until the closing minutes to add further to their tally with Mannone well worked, but the goals were well deserved when they arrived.

Bertrand was again involved in the third on 88 minutes, his ball into the six yard box proving impossible to handle for Jason Denayer who turned into his own net.

It got even better in stoppage time as Sunderland appeared to throw in the towel and allow Saints to pass through them with no charity shown as James Ward-Prowse and Shane Long exchanged passes before the sub steered the ball into the bottom corner.

What a difference one game, one week on the training ground, one signing, one formation change can make.

Now it’s all eyes on the EFL Cup final and with a quiet sense of confidence around the Saints camp.

Wembley, here we come.