Fernandes has one assist and has yet to score in this campaign and the playmaker has been criticised for his performances in the last two games in which United were held to draws by Crystal Palace and FC Twente.
Ten Hag was asked if the player is fatigued after a gruelling last season in which he played over 4,000 minutes for United before representing his country at EURO 2024.
"I think the team brings him in a situation. I think he is capable and he has proven already, so many times in the Premier League, he can create many chances," Ten Hag told reporters on Thursday ahead of Sunday's home game against Tottenham Hotspur.
"I am convinced he will not do differently. He will find his form.
"He is already creating chances but he will make final passes, he will score goals 100 per cent. It is just a matter of time."
United have scored only five league goals this season and sit 11th in the standings.
"We have players across the team who have the abilities to score. But it's clear you see all the opportunities we've created, we've not scored enough," Ten Hag said.
"You always work into a season, you have to build it, the structures in defending, structures in possession, of course. You start with the build-up, I think we have the structures quite right.
"Across all games we have more possession... and then it's about what we do with the possession. We bring the ball into the final third, we bring the ball into the box a lot... but we have to take advantage of it."
United have not beaten Spurs for two years and in a fixture that has traditionally produced goals Ten Hag said he expects an intense game against Ange Postecoglou's team who also have seven points and are 10th on goal difference.
"It always is against Tottenham and I think it is also our style as well. So I think it is going to be a very dynamic, attractive game," he said.
