Louis van Gaal has not given up on Manchester United’s on-loan striker Radamel Falcao, despite asking him to play in a youth team game this week.

United were knocked out of the FA Cup against Arsenal at Old Trafford on Monday night with Falcao an unused substitute. Less than 24 hours later Falcao played for United’s under-21 side against Tottenham, but his manager insists he still has a part to play at the club.

The 29-year-old Colombian joined United on a season-long loan deal from Monaco in August, but has so far contributed just four goals in 20 appearances.

Van Gaal had no explanation when asked to explain the striker’s poor form. He said: “We are looking for the solution.

“You can give fantastic performances in another country but not in the country that you are present for. That is not the first example and it will not be the last example.”

Falcao has been prolific at each of his former clubs, although he had managed only 20 appearances – scoring 11 goals – for the Ligue 1 club before joining United.

Van Gaal says Falcao needs to prove himself worthy of a starting place in the United frontline and he admits the resurgence of captain Wayne Rooney is making that more difficult.

“Now Wayne is playing there and Wayne is scoring so you always have to compare players with each other but you need also luck,” he said.

United host Tottenham in a crucial Premier League game on Sunday, with the teams separated by only three points in the table and both eyeing up a top four finish. United are 1.90 to defeat Spurs (4.06) at Old Trafford with the draw 3.36.