There are bound to be peaks and troughs in a footballer's career and Kobbie Mainoo faced some uncertainty at Manchester United following Ruben Amorim's appointment in November.

Mainoo was an unused substitute in Amorim's first game in charge against Ipswich Town and small doubts about his suitability to United's new formation gradually started to grow.

The assumption was that Mainoo and Manuel Ugarte would be Amorim's preferred midfield pairing. However, they have started together in just eight games and Amorim has described Ugarte as an "example", whilst suggesting Mainoo is "not the finished product" and "can do so much better".

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Mainoo is four years younger than Ugarte, who worked with Amorim at Sporting Lisbon, and can still take his game to another level, but Amorim's quotes about him have been interesting.

When Amorim discussed Mainoo and Ugarte earlier this month, he essentially joked the "guys in the media" believe the United academy graduate is already a world star and tried to explain why the 19-year-old still had some work to do to become a regular starter in his system.

There were signs of a blossoming understanding between Mainoo and Ugarte and they were excellent at Anfield, but there have also been some teething problems when they have started together.

Then Amorim ostensibly had a light-bulb moment as Mainoo started as a No.10 against FCSB in the Europa League on Thursday night. The Stockport-born youngster slotted in seamlessly, providing an assist for Diogo Dalot and scoring himself, and Amorim's quotes on Mainoo after the victory in Bucharest indicate that might become his permanent position.

During the post-match press conference, Amorim told reporters: "The Kobbie position today, we need time to understand the players, he was struggling a lot defending as a midfielder. Now more as a ten you can feel that he was so free, playing the ball near the box is really good, the small connections. We need time to work with the players and understand the best positions for them."

When speaking to MUTV, he added: "He's so technical and can change the game there, so I think it's a good position for him - we will see. But I'm really happy to see Kobbie enjoying the game a little bit more.

"Sometimes he's always worrying about the recovery, trying to defend, and I know that he is trying. Today I felt Kobbie was enjoying the game more and I am really happy for that."

Amorim went as far to say Mainoo was "struggling" in the deeper midfield position and perhaps there will be no going back, which would force United into a rethink for the summer window.

If Mainoo predominantly plays as a No.10 from now until the end of the season, United will need to sign someone to partner Ugarte and that wasn't supposed to be on the transfer agenda, however, it could become a priority because it's one of the most important positions on the pitch.

Fans shouldn't get too carried away and Mainoo will no doubt make more appearances alongside Ugarte in the pivot, but it does seem possible that his future lies in the No.10 role.

United will need to draw up a contingency plan in the transfer market and draft up a list of midfielders who could excel as a No.8 alongside Ugarte because Casemiro is expected to leave, Christian Eriksen is out of contract in the summer and Toby Collyer has made just a handful of first-team starts, so it's an area that will need to be addressed in the market.

Bruno Fernandes has started in three successive games in the pivot, but does his long-term future lie there with Amorim in charge? Playing Fernandes in that role on a permanent basis would mean a new midfielder might not be needed, although it would reduce his final third influence.

Amorim might need to amend his plans.