Manchester United manager Louis van Gaal says he is "not interested" in whether striker Radamel Falcao is happy to settle for a substitute's role and insisted the Colombian is not fit enough to last a full match.
Van Gaal said Falcao's lack of match fitness means he can only play for 20 minutes or so in the fast pace of the Premier League, and that the demands of the squad mean he has to continue in that role as cover for other strikers rather than work on his fitness.
Falcao is likely to be on the bench again at Southampton on Monday and asked if the striker was happy with that role, Van Gaal replied: "I am not interested in that. He has to follow my philosophy - do you understand that? I am here because of that.
"I have selected him in spite of the fact he can only play for 20 minutes, because the rhythm of the game in the Premier League is the highest.
"It's match fitness [he needs]. It would be a better contribution if he played with the second team but I cannot do that because on Tuesday we had the match against Stoke and Wayne Rooney was injured. I had to adapt to the needs of the selection [squad]."
Van Gaal was hugely relieved after a scan last week on a potential knee injury for Rooney showed there was no problem - the striker has become the key player for the Dutch manager after he chose him as his captain following the club's pre-season tour to the USA.
"Very good!" beamed Van Gaal, when asked about Rooney. "He will play."
He added: "We were in the USA when I decided to make him captain and not for one day have I regretted that. For me the most important thing is that he is captain of our team."
Van Gaal said he was impressed at the team spirit that has developed, highlighted by the Christmas party organised last week by Rooney.
"It was fantastic," van Gaal told MUTV. "Usually, I don't use words like this, but I think it showed the cohesion in our group from both the players and staff. My wife and I enjoyed it very much.
"The squad is very important, and that's why the timing of our Christmas party was fantastic - it showed the togetherness in the squad. I think we are in a good position."
The match at St Mary's is being built up as a battle between warring Dutch coaches van Gaal and Koeman, who fell out when they worked together at Ajax in 2004. The pair have refused to discuss their relationship but they appear to have buried the hatchet.
According to Dutch newspaper De Telegraaf, at a recent League Managers' Association meetings Van Gaal complimented Koeman on his work, told him: "You have a good team," and clapped him on the shoulder.