Louis VAN GAAL has suggested that the intervention of super-agent Jorge Mendes has not helped Radamel Falcao's chances of securing a permanent move to the club.
Mendes publicly queried why his client has not featured more at Old Trafford as he seeks to prove his fitness and turn a loan move into a lucrative, longer-term contract.
It would cost well in excess of £40m for United to sign Falcao permanently, but there has been little evidence that the South American, 28, would justify such an outlay.
Mendes suggested earlier this week that United were not using him enough.
"It is very difficult for Manchester United fans. They have an absolutely brilliant player, one of the very best in the world, who would without any doubt play 90 minutes of the match, every time, with any other club," he said.
"Falcao will play in one of the very best clubs in the world next season, whether that is Manchester United or not. The truth is, right now, we don't know what will happen."
Van Gaal brushed off the claims. Asked if they were unhelpful, he said: "Of course but it doesn't interest me.
"I think it is the obligation of the manager that you observe, analyse your selection, that you make a game plan, that you communicate with your players and then you make a decision that the players understand."
United may have to tread carefully with the powerful Mendes, especially as he will have an influence over the future of another high-profile Old Trafford client - goalkeeper David de Gea - but Van Gaal (right) was in combative mood as he explained why the Colombian's game time has been limited.
The Dutch coach said Falcao striker must do more to establish himself at Old Trafford. He was left out of the squad for United's home defeat by Southampton last week, raising questions as to whether he can regain the form and fitness that once made him one of the world's most-wanted forwards.
"He has to prove himself," said Van Gaal. "It is down to the quality of the training sessions and quality in his matches.
"I have to have a game plan. I explained it after the Southampton game.
"If a player cost £95m or £5,000, it does not make any difference for me. You have to prove yourself. I have to be like that even if it is difficult for the outside world to understand.
"I cannot say why one player is picked over another. That is for the players, not for you. I compare and I have to decide. I have a game plan.
We have the qualities of the opposition and then I have to choose and compare."
United continue to be linked with new recruits this month, although Van Gaal suggested there may not be much transfer activity.
"I don't think that we shall be very active because not many players of a certain level are available and when we buy a player he has to be better than our players now," said the Dutchman.
Van Gaal also admitted recent results demonstrated how much further the team needed to develop to challenge for the title again.
"We want to be champions but then you have to win games versus Southampton and Aston Villa away," he said.
"When you're not doing that you can't be champions. Our goal is to play Champions League.
"We have played 21 matches and we are in the area of the four but we have to fight for it because a lot of other teams are willing the same goal."
Van Gaal's system of three central defenders has been questioned throughout the season, but he maintains it can work given the personnel at his disposal.
"What is the most suitable system for the players you have?" he said.
"I have played with a lot of different systems in my career so for me it is always the biggest argument is the quality of your players. You see the quality then you pick a system."
Although United were beaten by Southampton, Van Gaal said the recent game at Spurs showed how the formation can operate successfully.
He said: "You pick a match like that [Southampton] but I can pick up a match like Tottenham Hotspur away, a top-six club, and we played with creativity and could have scored a lot of goals."
United could be without Robin van Persie for today's trip to Queens Park Rangers because he has an ankle injury. © Daily Telegraph, London.