The Cameroonian has had a difficult start to his Red Devils career, conceding 20 times in 13 appearances, and he has faced heavy criticism for a number of mistakes this season.
Ten Hag has continued to back Onana amid his struggles, though, and the 27-year-old managed to keep a clean sheet in Wednesday's European contest with Copenhagen.
The summer arrival from Inter Milan saved a last-gasp penalty in the clash at Old Trafford after Scott McTominay had been penalised for a high boot.
Ten Hag hailed Onana for his vital contribution to the hugely important three points, but the Dutchman said that it is vital for every player at the club to show consistency.
«I know how good he is and the skills he has. At United, you have to show it every game, having the right focus and mindset,» Ten Hag told reporters on Tuesday evening.
«If he has that, he will perform. I think it's very important for him. Of course, he had some criticism but now he saves the points for the lads, it was a brilliant save just after half-time also.
»You can see this team is growing, we have a lot of setbacks as a team but, in the dressing room, we deal with it and, slowly, we are coming forward.
«Playing at Manchester United, we have to win. When the team is not winning, everyone is criticised and some players get more criticism than others, especially Harry [Maguire] and Andre. It was, more or less, over the top but this gets confidence for both of them and will help the team to make the next step.»
Maguire scored the only goal of the contest against Copenhagen,
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