After a while the questioning about Louis van Gaal began to bore Ronald Koeman, but something else also bothered him: his answer.

He had known that addressing Southampton’s Monday night rendez-vous with Manchester United would mean talking about his rivalry with his compatriot and he initially responded by insisting the pair now enjoy a good relationship, that the “working problem” which caused them to fall out bitterly at Ajax a decade ago was buried in the past. But then he felt the need to adjust his description of their relationship: “I don’t say good, it’s correct. That’s the best word.”

It is clear that the affection that used to unite the duo when Koeman served as Van Gaal’s assistant manager at Barcelona in the late 1990s has not returned but Koeman was keen to indicate any bad blood that lingers does not distract them from work.

Then the Southampton manager terminated the inquiries with a decisive: "Too much questions about him."

Which is fair enough. Because while a sub-plot involving two famous Dutchmen using Premier League teams as proxies to fight the latest battle in a long-running feud with each other is seductive, the most significant feature of the duel at St Mary's will be what it reveals about each manager's club.

Important clash

If there was one match this season for which Koeman would have wished to have a full-strength team, it is probably this one, not merely for personal reasons but also because defeats in their last two matches make this a particularly important game.

The club has already defied expectations this season by making a strong start despite a summer of high player turnover, now they must do so again.

Losses to Manchester City and Arsenal, following earlier reverses to Tottenham Hotspur and Liverpool, increased many people’s suspicion that Southampton’s good start owed much to a favourable fixture list – beating United would help prove that they have enough quality to stay in the upper reaches of the table.

Providing such evidence will mean showing the depth of the Southampton squad and Koeman will find out whether his side can cope with key losses. The absence of Toby Alderweireld from central defence is an obvious worry, as the Belgian has formed a solid partnership with Jose Fonte since arriving on loan from Atletico Madrid in September.

Alderweireld’s hamstring trouble is likely to mean a start for Maya Yoshida, who is neat on the ball but has yet to demonstrate enough strength or savviness to suggest he can help shut out an in-form United attack.

Patching up

There has been some patching up in midfield in recent weeks and that is going to continue, as Morgan Schneiderlin will miss the match against United and Jack Cork, his usual deputy, is out for up to two months.

With James Ward-Prowse at least two weeks away from a return, Koeman may have to turn to 19-year-old Harrison Reed. That increases the pressure on Victor Wanyama to prolong the excellent form that he has displayed this season, the Kenyan bringing power and a new thrust to the base of midfield.

Southampton look stretched further forward too. With Ward-Prowse and Jay Rodriguez still missing, Koeman is reliant on a small clutch of attackers including Dusan Tadic, Sadio Mane, Shane Long, Steven Davis and Graziano Pelle. They have all gone slightly off the boil in recent weeks. But Nathaniel Clyne, Ryan Bertrand and the Serb all retain the ability to create chances nonetheless. Pelle has not scored for six matches partially because the service to him has dwindled slightly.

Koeman will not panic. He transmits a composure and confidence in his method that translate to the team. Southampton will be confident they can play through adversity.

Though depleted, Southampton can beat United, but even if they fall to a third loss in a row, Koeman says he will not lose faith. “It’s 38 games and I wasn’t celebrating a party after 10 games, I will not be crying after four [winless] games if we don’t win against United.” Guardian Service