Ruben Amorim has admitted to taking a significant risk in not replacing Marcus Rashford in the January transfer window but is “thankful” the Manchester United striker is now in Birmingham after securing a loan move to Aston Villa.

United are struggling badly to score goals but opted against signing another striker last month at Amorim’s request despite loaning out Rashford and fellow forward Antony to Real Betis.

Amorim acknowledged it was a big gamble at a time when results are nosediving but the Portuguese insisted it was one he was prepared to take rather than run the risk of more transfer mistakes – and he will cop for the blame if the decision backfires.

“Like we said before, we are fighting for our jobs until the summer,” said Amorim, whose side face Ruud van Nistelrooy’s Leicester City in the FA Cup fourth round at Old Trafford on Friday night.

“So I am just focused on these games. Thankfully about Marcus, he is in Birmingham now with Unai [Emery], so you can take these questions to another coach. We are just focused on our players.

“That [the responsibility] is clear. It is also exciting. I know when I choose this profession that you have the risk of results and I knew when I came here I look at the schedule, I looked at the team, and I understood my decision of changing everything in the middle of the season without new signings, it is a danger for a coach.

“But since day one, with good results or bad results I have a clear idea of what I want to do and I take these risks because in the end I think it’s going to pay off. But I’m not naive, I said that many times, this is a sport of results and we are in a difficult situation.

“What I feel is that the club is taking its time, we know the urgency of the moment of the team, [but] everybody here doesn’t want to make the same mistakes of the past.

“In the summer we will see, but like I said, we are being really careful with transfers because we did some mistakes in the past.”

Amorim has lost seven of his 13 Premier League games since replacing Erik ten Hag as head coach in November and United languish 13th in the table with a minus-six goal difference.

“I think it is a moment that is hard to turn things around in just a few games,” he said. “It’s going to be like that, really hard until the end of the season, then we are taking that risk that you talk about because we want a different thing in our team and different profiles. That is my area, so it was my decision to do that.

“We are taking some risks but it is the way we want to proceed. We want to win some games, we can improve our team, we will have time to train because I’m always complaining about the time to train. So now we have time to train, and the team will improve. The players, I want a certain type of players with a different profile and we are changing right away.”

United confirmed that Lisandro Martinez was “going to be out for a while” with a cruciate knee ligament injury but said the club still do not know the full extent of the problem. He also said that Luke Shaw has a “small issue in a different area” from his last hamstring injury and that they were handling the England defender’s return carefully. Shaw has not started a game for the club for 12 months.

Amorim said new signings Patrick Dorgu and Ayden Heaven were ready to play against Leicester but would decide on Friday whether to include them in the squad.