One Southampton FC factor could concern John Mousinho and Portsmouth - it's a topic that splits opinion | OneFootball

Analytics have Southampton underperforming their xG massively so far this season

For the first time since April 2012, Southampton and Portsmouth are going head-to-head in league action.

The two sides have largely been on opposite trajectories over the last decade or so, as the Saints have gone from Europa League challengers to Premier League relegation battles, whilst Pompey have had to endure seasons in League Two and League One.

Now, the two sides are finally back in the same division and will be taking each other on at midday on September 14.

Despite plenty of pre-season predictions having Southampton among those to make an immediate bounce back to the Premier League, it's actually John Mousinho's side who come into this one with the better form, having picked up seven points in comparison to the Saints' five through four games.

Despite Will Still's short Saints tenure so far producing just one league win, that's not been for the lack of trying, and the vast number of chances created will have Portsmouth wary ahead of the biggest game of their season.

Southampton lead the xG charts in the Championship this season ahead of Portsmouth clash

For those who indulge themselves in data-driven content, Southampton currently lead the xG charts in the Championship this season.

The Saints have registered a whopping 9.3 expected goals through their opening four games, despite only finding the net six times. They've also created 14 big chances, and have missed eight of them.

Now, it's worth noting that 4.14 of that 9.3 total came on their opening day win against Wrexham, who themselves have the highest expected goals against this season, indicating that they are the worst defensive side through four games.

They registered just 0.75 in their draw against Ipswich Town, and then 2.59 against Stoke City and then 1.81 against Watford last time out.

Again, an asterisk is formed next to the loss against Mark Robins' Stoke side, as a lot of that 2.59 was generated after Divin Mubama was sent off with half an hour to go.

But, whilst questions can be asked about how easy it has been to get that number up, what can't be disputed is Southampton's ability to create those chances.

It's been a slow start due to a lot of player turnover at St Mary's this season, but now Will Still has a couple of weeks with those who aren't away on international duty to work on things — one of which will be turning these chances into goals more regularly.

Therefore, Portsmouth will need to be on it from the off if they are to taste victory against their bitter rivals.

Analytics go out the door on Derby Day

Whilst these statistics are always helpful in analysing how a side has started the season and forming conclusions on who may have the upper hand in an upcoming match, this is a derby that, in league action at least, is 13 years in the making.

And for a league win in this matchup, you have to go even further back to 2005, when Portsmouth beat Southampton 4-1.

Therefore, whilst tactics are important, it's arguable that the raw emotion of the day will be enough to charge either side on towards the all-important three points and bragging rights over their rivals until late January when the two meet at Fratton Park.

Especially from a Portsmouth standpoint, who have had to scratch and claw their way back to this point, whilst their south coast rivals have revelled in top-half Premier League finishes and European tours.

John Mousinho and his side will be aware of the threat Southampton pose, even more so now with the likes of Tom Fellows and Finn Azaz in the side, too, but on Derby Day, sometimes it's all about who shows more passion and a willingness to win on the field, rather than fancy play and a plethora of chance creation, which takes you over the line.