The Scotland international signed from Leeds United this week for a Championship record £11million and is eager to make his mark for Felix Magath's promotion hopefuls.
Speaking after the 2-0 win at Fir Park, McCormack told Sky Sports News: "I thoroughly enjoyed it, coming back to one of my old clubs, and it was good to be on the winning side.
"I only joined up on Wednesday so I have only done three days' training so I didn't think I would be playing today and then I played 90 minutes so it was a nice surprise.
"I can only just add to the group that is already here. There are some very good players here. We are still only two weeks into pre-season, there are four weeks to go so there is still plenty of work to be done.
"There is no pressure on me; the only pressure is to score goals, the price tag is irrelevant. You are only worth what someone is willing to pay for you. I will try my best and hopefully that will be good enough.
"It's a different team and a different city but I will still be playing football and hopefully it will be a successful season."