Ronald Koeman believes.

Plenty outside of Saints might not, but that is of no consequence to him.

That is because the man who reached the pinnacle of the game as a player is certain of the quality that is currently at his disposal as a manager.

And, as he takes his team to fellow top-four contenders Manchester United today, he asks a simple question of those quizzing him about their Champions League hopes: “Why not?”

“We have the qualities, we have the players and, at the moment, we have to believe that if we don’t have really bad injuries of some key players then why not?” he said.

Saints’ hopes of finishing in the top-four this season would certainly be significantly boosted if they can secure a first league win in 27 years at Old Trafford tomorrow.

Heading into the weekend holding onto fourth place, Koeman’s men would climb above United and end the day in third with a victory.

“Games like Man United on Sunday are good tests to see if the players believe in the qualities of the team and if we can reach that kind of position in the table,” said Koeman, who clearly has every confidence in his side.

“We don’t have the pressure that Arsenal and Man United have to be the first teams on the tables.

“But we showed against Chelsea, we showed against Arsenal that we can fight for that position in the league and we have another test this Sunday.”

Koeman added: “We played 20 games [so far this season]. In ten games, we had clean sheets.

“There’s no better example why we should believe.

“That means that we have a good defence, we have a good team organisation when we don’t have the ball.

“And that’s more important, that’s more reasons to give the players to have that belief in the game.

“It’s not lucky. I really believe that we can do it again.”

Koeman is aware that his squad is not as deep as the Premier League’s most established sides and, although the likes of Toby Alderweireld, Ryan Bertrand, Victor Wanyama and Fraser Forster have plenty of Champions League and title-winning experience, many others do not.

But the Saints boss says that there is only one way to get it.

“The players don’t have the experience that most of the players of United, Arsenal, have,” he said. “We don’t have that experience.

“You need it by doing and playing for those kind of positions in the table.

“Sunday is another test to show that we really can fight for that position in the table.”

Koeman, a European Cup winner in his legendary playing days, knows that he has a key role to play in encouraging his players towards the finish line, and he is careful to make sure he does not display any signs of agitation as Saints get closer and the pressure increases.

“In my opinion, it’s important that the manager is calm, because, if the manager is very nervous or shouting or doing crazy things out of the pitch, then how you can ask the players to be calm on the pitch?” he said.

“No. I’m not so different. I try to be myself and I think that’s the most important.

“Ok, every player and manager has his own emotions and one person is showing that more often than other persons, but that’s normal and I prefer to be myself outside the pitch.”

Koeman goes head-to-head tomorrow with the man who is arguably his biggest nemesis in the game – Louis van Gaal.

The pair’s relationship has been a frosty one for many years.

They go back a long way, having worked together at Barcelona, where Koeman was on the coaching staff under Van Gaal.

They were then reunited at Ajax, where the problems really began, with Koeman – who was the manager – unhappy at technical director Van Gaal’s desired input into first-team matters.

A series of falling-outs occurred, as the relationship deteriorated badly, with the tension having simmered in the background ever since.

There was an amicable meeting at St Mary’s last month, though, as Van Gaal got the better of Koeman, with United winning 2-1, despite being dominated by the hosts.

Saints gifted their opponents the win that night, making two bad defensive errors that were both punished by Robin van Persie.

While United’s overall performance was poor, Koeman believes Van Gaal has improved his side since then.

“I think that the team is stronger now, because I think the system – they are used more to that system that they play and they have less injuries and I think they are eight, nine games unbeaten,” he said.

“That brings confidence to the players. If you have [Angel] Di Maria, you have [Radamel] Falcao, you have Van Persie, you have [Wayne] Rooney, you have [Juan] Mata – come on, please. You have great players.”

Indeed, Koeman believes with the quality at his disposal that Van Gaal should have United competing for the Premier League title.

He also does not think that he will be afforded too much time to get them to that level.

“It’s up to him,” he said. “If he needs two years more, give him two years more.

“But I think always in football, of course maybe he is doing different to other managers, but I don’t believe in football that you need two years or one year.

“No. It’s all about qualities of the players and they have to do that. And the better the players, the easier it is for the manager.”

Koeman added: “It’s an easy answer as a manager to say ‘I need time.’ You don’t have time in football.

“OK, you need adaptation of the players.

“I think sometimes they are more excuses of the people than to expect something.

“Football is the same in Holland, in Germany.

“The players are better in Germany and England than we have in Holland, most of the players.

“But my job as a manager is not so different to what I did in the last three years in Feyenoord – managing a football team.

“OK, new players. I have better players than I had in the last three seasons. It has to be easier, that adaption. It’s about the quality of the players.”

This afternoon, we will see if Saints’ quality is enough to overcome United and push the club one step closer to the Champions League.