Di Maria broke the club's transfer record when he completed his £59.7m move from Real Madrid, while Herrera joined for £32m from Athletic Bilbao.
The pair have started life at Old Trafford effortlessly with a combined total of five goals and four assists, while the former claimed both the club's Player and Goal of the Month.
And 18-year-old midfielder Pereira claims the pair continue their form into training.Â
When asked who the best player at training is, the Belgian said: "Everyone's been really good but the best in training, for me, is Angel Di Maria. He's very good in training as well as in matches.Â
Newspaper Review - Sunday 12 October
The best in training, for me, is Angel Di Maria
"I also admire Ander Herrera for the way he plays in my position but also the way he speaks to the other players."
And on the best goal he's witnessed at the Aon Training Complex, he added: "I can think back, a couple of weeks ago, to when Di Maria scored an unbelievable goal.Â
"We did some finishing after training with the forwards and he scored a brilliant strike.
"He controlled it and bounced the ball into the top corner. It was incredible."