The Serbia international, who joined in a £40m deal from champions Chelsea last month, played a full part as the Red Devils cruised to a comfortable victory at Old Trafford on Sunday afternoon.
Matic has now challenged his teammates to maintain their high performance levels throughout the duration of the campaign, including midfield partner Paul Pogba who was given the freedom to push into advanced positions against the Hammers.
"It was a really important game for us to start well with the three points," he told Sky Sports News. "They were very compact but after the first goal we had more space. I am very happy for the team and we we will have more confidence going into the next game.
"The manager told me I have to do my job, Paul has to do his. I am very happy everyone gave their best against a good team. We have to continue to work like this."