United host Anderlecht on Thursday night in the return leg of their Europa League quarter-final, with the tie finely poised at 1-1 from last week.
Having started so impressively after his big-money move from Monaco in 2015, the 21-year-old's second season at OId Trafford has been a struggle.
In a recent press conference, Manchester United manager Jose Mourinho answered questions about numerous team's star players, including Marcus Rashford, Anthony Martial, and Henrikh Mkhitaryan.
"I go in the direction of the players, they have to also come in my direction", said the Portuguese.
"I think we have seen the best and worst from United in this game", Keane told ITV Sport.
"Some players don't know what makes me trust a player but Marcus I trust".
Marcus Rashford scored the victor in extra time to move Man United past Anderlecht 3-2 on aggregate in the Europa League.
Wayne Rooney is still capable of playing a part in Manchester United's bid to conquer the Europa League.
Giving his thoughts on the contest, Anderlecht boss Rene Weiler said: "I'm really happy with the way we played but obviously less happy with the result".
Speaking in his press conference, Mourinho believes Martial still has the ability to become a very successful player. Both pursuits will be much more hard of Ibrahimovic isn't available, but that could very well be the Red Devils' reality.
United's win over Chelsea enhanced their chances of securing a top-four finish in the league, leaving them four points behind fourth-place Manchester City with a game in hand. Yes I think. Do I think he can be successful for me?
"No injuries from the game [Sunday's 2-0 win over Chelsea], but also no-one recovered".
"He's working, he's improving and, if in this session the answer is positive, I will select him to be on the bench".
"We have felt that kind of performance coming", said the versatile England global, United's captain against Chelsea. I do not know the extent of his injury, of course, but I saw him in there and he was optimistic. We need everyone we can.
Manchester United have won all their home games in this season's Europa League and are confident of getting the job done against Anderlecht tonight at Old Trafford.
"He is my goalkeeper for tomorrow and he was my goalkeeper in other matches, but he is not my goalkeeper for the Europa League".
"We played very well in the first half".
"I never like to do that, complete separation".