During his first stint as Barcelona manager, Louis van Gaal invited Ronaldo Koeman to become a part of his coaching staff, giving him his first taste of training players after retiring from playing.

Van Gaal had been warned that Koeman was egotistical but this didn’t stop him from giving the 35-year-old some important experience.

Having won three league titles, the European Cup, the UEFA Cup and UEFA Super Cup and several other trophies with Ajax, Van Gaal returned to the club as a technical director in 2004.

Koeman was the manager at the time and had won two titles in three years. During the pre-season ahead of the 2004-05 season, Van Gaal took Koeman to one side to discuss his performance as manager. Koeman reminded Van Gaal that he was answerable to the general manager of the club, not Van Gaal, and that was the beginning of the rift.

Van Gaal would talk to the players during training, despite Koeman being told this wouldn’t happen, and the rift grew bigger.

On one occasion, Van Gaal called over a young Zlatan Ibrahimovic and gave him some advice, telling him he needed to get to the near post more often. Moments later, Ibrahimovic scored, leading Van Gaal to exaggerate his celebration, much to Koeman’s frustration.

Ibrahimovic claims he was often the cause of their falling out, with Van Gaal not wanting to waste the striker in league games when the title was already wrapped up, and instead save him for Champions League games.

“Koeman went mad,” he said. “He was furious at Van Gaal. He felt that statement meant his hands were tied and limited his chances to fight for me.”

Van Gaal left the club and was appointed manager of AZ Alkmaar. After winning the title in 2009, the second in the club’s history, he left for Bayern Munich. Koeman was named his replacement but was sacked in December after losing seven of the opening 16 games.

The two men meet again this evening and it’s obvious that both will be desperate for the win, even though neither a prepared to talk about the falling out now.

“It is no issue. If we see each other, we shake hands. And that’s enough,” Koeman said when asked about their relationship. “The game is Southampton v Manchester United, and the game needs that attention. It is not about Ronald Koeman and Louis van Gaal. That is private. That was a working problem…it is not an issue, it is eight, nine years ago and now I prefer to talk about the game.”

Van Gaal has reiterated this sentiment.

“I don’t have to describe my relationship with the trainer of the opponent,” he said. “I think that’s private. We play against Southampton and we have to speak about Southampton and not their trainer,” van Gaal said. “Ronald Koeman is a very good coach and I know that he can do that. I think it’s surprising that a club like Southampton is in that position now. That’s always down to the trainer, the players and the staff. When you do that, it’s very good.”